diff --git a/build.gradle b/build.gradle
new file mode 100644
index 0000000..79eca26
--- /dev/null
+++ b/build.gradle
@@ -0,0 +1,18 @@
+group 'ru.spbau.mit.lobanov'
+version '1.0-SNAPSHOT'
+
+apply plugin: 'java'
+
+sourceCompatibility = 1.8
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testCompile group: 'junit', name: 'junit', version: '4.11'
+    // https://mvnrepository.com/artifact/com.google.guava/guava
+    compile group: 'com.google.guava', name: 'guava', version: '21.0'
+
+    compile group: 'org.jetbrains', name: 'annotations', version: '13.0'
+}
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 0000000..6ffa237
Binary files /dev/null and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000..77443a8
--- /dev/null
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,6 @@
+#Thu Mar 30 14:15:21 MSK 2017
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-3.1-bin.zip
diff --git a/gradlew b/gradlew
new file mode 100644
index 0000000..9aa616c
--- /dev/null
+++ b/gradlew
@@ -0,0 +1,169 @@
+#!/usr/bin/env bash
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn ( ) {
+    echo "$*"
+}
+
+die ( ) {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=$((i+1))
+    done
+    case $i in
+        (0) set -- ;;
+        (1) set -- "$args0" ;;
+        (2) set -- "$args0" "$args1" ;;
+        (3) set -- "$args0" "$args1" "$args2" ;;
+        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Split up the JVM_OPTS And GRADLE_OPTS values into an array, following the shell quoting and substitution rules
+function splitJvmOpts() {
+    JVM_OPTS=("$@")
+}
+eval splitJvmOpts $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS
+JVM_OPTS[${#JVM_OPTS[*]}]="-Dorg.gradle.appname=$APP_BASE_NAME"
+
+# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
+if [[ "$(uname)" == "Darwin" ]] && [[ "$HOME" == "$PWD" ]]; then
+  cd "$(dirname "$0")"
+fi
+
+exec "$JAVACMD" "${JVM_OPTS[@]}" -classpath "$CLASSPATH" org.gradle.wrapper.GradleWrapperMain "$@"
diff --git a/gradlew.bat b/gradlew.bat
new file mode 100644
index 0000000..f955316
--- /dev/null
+++ b/gradlew.bat
@@ -0,0 +1,84 @@
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS=
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windows variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/settings.gradle b/settings.gradle
new file mode 100644
index 0000000..5d3aeb1
--- /dev/null
+++ b/settings.gradle
@@ -0,0 +1,2 @@
+rootProject.name = 'exam work'
+
diff --git a/src/main/java/HashMD5.java b/src/main/java/HashMD5.java
new file mode 100644
index 0000000..f047518
--- /dev/null
+++ b/src/main/java/HashMD5.java
@@ -0,0 +1,175 @@
+import org.jetbrains.annotations.NotNull;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.ArrayList;
+import java.util.concurrent.ForkJoinPool;
+import java.util.concurrent.RecursiveTask;
+
+public class HashMD5 {
+
+    /**
+     * Run single-thread calculating of MD5-hash of given file
+     *
+     * @param file target file
+     * @return MD5-hash
+     * @throws NoSuchAlgorithmException if md5-algorithm was not found
+     * @throws FileNotFoundException    if some file was not found
+     * @throws IOException if its occured during file reading
+     */
+    private static byte[] hashFile(@NotNull File file) throws NoSuchAlgorithmException, IOException {
+        if (!file.exists()) {
+            throw new FileNotFoundException(file.getAbsolutePath());
+        }
+        FileInputStream input = new FileInputStream(file);
+        byte[] buffer = new byte[1024];
+        int readBytes;
+        MessageDigest md5 = MessageDigest.getInstance("MD5");
+        do {
+            readBytes = input.read(buffer);
+            if (readBytes != -1) {
+                md5.update(buffer, 0, readBytes);
+            }
+        } while (readBytes != -1);
+        return md5.digest();
+    }
+
+    /**
+     * Run single-thread calculating of MD5-hash of given directory
+     *
+     * @param file target directory
+     * @return MD5-hash
+     * @throws NoSuchAlgorithmException if md5-algorithm was not found
+     * @throws FileNotFoundException    if some file was not found
+     * @throws FilesNotRetrievedException    if fail to get inner files
+     * @throws IOException if its occured during file reading
+     */
+    private static byte[] hashDirectory(File file) throws IOException, NoSuchAlgorithmException {
+        if (!file.exists()) {
+            throw new FileNotFoundException(file.getAbsolutePath());
+        }
+        if (!file.isDirectory()) {
+            throw new IllegalArgumentException("Directory was expected, but file was found");
+        }
+        MessageDigest md5 = MessageDigest.getInstance("MD5");
+        md5.update(file.getName().getBytes());
+        File[] files = file.listFiles();
+        if (files == null) {
+            throw new FilesNotRetrievedException("At directory: " + file.getAbsolutePath());
+        }
+        for (File f : files) {
+            md5.update(hash(f));
+        }
+        return md5.digest();
+    }
+
+    /**
+     * Run single-thread calculating of MD5-hash of given file
+     *
+     * @param file target file
+     * @return MD5-hash
+     * @throws NoSuchAlgorithmException if md5-algorithm was not found
+     * @throws FileNotFoundException    if some file was not found
+     * @throws FilesNotRetrievedException    if fail to get inner files
+     * @throws IOException if its occured during file reading
+     */
+    public static byte[] hash(File file) throws IOException, NoSuchAlgorithmException {
+        return file.isDirectory() ? hashDirectory(file) : hashFile(file);
+    }
+
+    /**
+     * Run multi-thread calculating of MD5-hash
+     * of given file using ForkJoinPool
+     *
+     * @param file target file
+     * @return MD5-hash
+     * @throws NoSuchAlgorithmException if md5-algorithm was not found
+     * @throws FileNotFoundException    if some file was not found
+     * @throws FilesNotRetrievedException    if fail to get inner files
+     * @throws IOException if its occured during file reading
+     */
+    public static byte[] hashParallel(File file) throws IOException, NoSuchAlgorithmException {
+        ForkJoinPool pool = new ForkJoinPool();
+        byte[] result;
+        try {
+            result = pool.invoke(new ParallelHashCalculator(file));
+        } catch (ForkJoinTaskException e) {
+            if (e.getCause() instanceof IOException) {
+                throw (IOException) e.getCause();
+            } else if (e.getCause() instanceof NoSuchAlgorithmException) {
+                throw (NoSuchAlgorithmException) e.getCause();
+            }
+            throw e; // unknown error
+        }
+        return result;
+    }
+
+    /**
+     * Special class which implement RecursiveTask to
+     * run multi-thread calculations
+     * Calculate MD5-hash of file or directory given in constructor
+     */
+    private static class ParallelHashCalculator extends RecursiveTask<byte[]> {
+
+        private final File targetFile;
+
+        private ParallelHashCalculator(File targetFile) {
+            this.targetFile = targetFile;
+        }
+
+        @Override
+        protected byte[] compute() {
+            if (!targetFile.isDirectory()) {
+                try {
+                    return HashMD5.hashFile(targetFile);
+                } catch (Exception e) {
+                    throw new ForkJoinTaskException(e);
+                }
+            }
+            MessageDigest md5 = null;
+            try {
+                md5 = MessageDigest.getInstance("MD5");
+            } catch (NoSuchAlgorithmException e) {
+                throw new ForkJoinTaskException(e);
+            }
+            md5.update(targetFile.getName().getBytes());
+            File[] files = targetFile.listFiles();
+            if (files == null) {
+                throw new ForkJoinTaskException(new IOException("Cant retrieve files"));
+            }
+            ArrayList<ParallelHashCalculator> calculators = new ArrayList<>();
+            for (File file : files) {
+                ParallelHashCalculator calculator = new ParallelHashCalculator(file);
+                calculator.fork();
+                calculators.add(calculator);
+            }
+            for (ParallelHashCalculator calculator : calculators) {
+                md5.update(calculator.join());
+            }
+            return md5.digest();
+        }
+    }
+
+    /**
+     * Exception, thrown if file.listFiles() returned null
+     */
+    public static class FilesNotRetrievedException extends IOException {
+        private FilesNotRetrievedException(String message) {
+            super(message);
+        }
+    }
+
+    /**
+     * Uncheckable exception to wrap exception which occur
+     * during calculation in ForkJoinPool
+     */
+    private static class ForkJoinTaskException extends RuntimeException {
+        private ForkJoinTaskException(Throwable cause) {
+            super(cause);
+        }
+    }
+}
diff --git a/src/main/java/Tester.java b/src/main/java/Tester.java
new file mode 100644
index 0000000..611c419
--- /dev/null
+++ b/src/main/java/Tester.java
@@ -0,0 +1,18 @@
+import java.io.File;
+import java.util.Arrays;
+
+public class Tester {
+    public static void main(String[] args) throws Exception {
+//        String path = args[0];
+        String path = "C:\\workspace";
+
+        long timeStart = System.currentTimeMillis();
+        System.out.println("Run single thread calculating");
+        System.out.println("Result: " + Arrays.toString(HashMD5.hash(new File(path))));
+        System.out.println("Time: " + (System.currentTimeMillis() - timeStart) + " mills");
+
+        System.out.println("Run multi thread calculating");
+        System.out.println("Result: " + Arrays.toString(HashMD5.hashParallel(new File(path))));
+        System.out.println("Time: " + (System.currentTimeMillis() - timeStart) + " mills");
+    }
+}
diff --git a/src/test/java/HashMD5Test.java b/src/test/java/HashMD5Test.java
new file mode 100644
index 0000000..27e59f8
--- /dev/null
+++ b/src/test/java/HashMD5Test.java
@@ -0,0 +1,54 @@
+import com.google.common.io.Files;
+import org.junit.Test;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.security.NoSuchAlgorithmException;
+import java.util.Arrays;
+
+import static org.junit.Assert.*;
+
+public class HashMD5Test {
+
+    private static final String workspace = "test_workspace";
+
+    private static void fillFile(String fullPath, String name) throws IOException {
+        File f = Paths.get(fullPath, name).toFile();
+        Files.createParentDirs(f);
+        PrintWriter out = new PrintWriter(f);
+        out.write(String.valueOf(Math.random()));
+        out.write(String.valueOf(Math.random()));
+        out.close();
+    }
+
+    @Test
+    public void constancyTest() throws IOException, NoSuchAlgorithmException {
+        fillFile(workspace,"a.txt");
+        byte[] result1 = HashMD5.hash(Paths.get(workspace, "a.txt").toFile());
+        byte[] result2 = HashMD5.hash(Paths.get(workspace, "a.txt").toFile());
+        assertArrayEquals(result1, result2);
+    }
+
+    @Test
+    public void similarityTest() throws IOException, NoSuchAlgorithmException {
+        fillFile(workspace,"a.txt");
+        byte[] result1 = HashMD5.hash(Paths.get(workspace, "a.txt").toFile());
+        byte[] result2 = HashMD5.hashParallel(Paths.get(workspace, "a.txt").toFile());
+        assertArrayEquals(result1, result2);
+    }
+
+    @Test
+    public void folderHashTest() throws IOException, NoSuchAlgorithmException {
+        fillFile(workspace,"a.txt");
+        fillFile(Paths.get(workspace, "folder").toString(),"a.txt");
+        byte[] result1 = HashMD5.hash(Paths.get(workspace, "a.txt").toFile());
+        byte[] result2 = HashMD5.hash(Paths.get(workspace, "folder", "a.txt").toFile());
+        byte[] result3 = HashMD5.hashParallel(Paths.get(workspace, "folder", "a.txt").toFile());
+        assertTrue(!Arrays.equals(result1, result2));
+        assertArrayEquals(result2, result3);
+    }
+}
\ No newline at end of file