diff --git a/src/main/java/hse/java/practice/echochat/EchoChatServer.java b/src/main/java/hse/java/practice/echochat/EchoChatServer.java
index bc11062..6d7bbbd 100644
--- a/src/main/java/hse/java/practice/echochat/EchoChatServer.java
+++ b/src/main/java/hse/java/practice/echochat/EchoChatServer.java
@@ -1,4 +1,117 @@
 package hse.java.practice.echochat;
 
-public class EchoChatServer { 
-}
+import java.io.*;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.nio.charset.StandardCharsets;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class EchoChatServer {
+    private static final Set<ClientHandler> clients = ConcurrentHashMap.newKeySet(); // потокобезопасный
+    static void main(String[] args) {
+        if (args.length == 0) {
+            System.out.println("Usage: java EchoChatServer <port>");
+            return;
+        }
+
+        int port = Integer.parseInt(args[0]);
+
+        try (ServerSocket serverSocket = new ServerSocket(port)) {
+            System.out.println("Chat server started on port " + port);
+            while (true) {
+                Socket socket = serverSocket.accept(); // соед с конкретный клиентом
+                ClientHandler clientHandler = new ClientHandler(socket); // обьект для обслуживания клиента
+                Thread thread = new Thread(clientHandler); // тред для клиента, позволяет параллелить, принимает обьект runnable
+                thread.start(); // запускает clienthandler.run
+            }
+        } catch (IOException e) {
+            System.err.println("Server error: " + e.getMessage());
+        }
+    }
+
+    private static void broadcast(String message, ClientHandler sender) {
+        for (ClientHandler client : clients) {
+            if (client != sender) {
+                client.send(message);
+            }
+        }
+    }
+
+    private static class ClientHandler implements Runnable {
+        private final Socket socket;
+        private BufferedReader reader;
+        private BufferedWriter writer;
+        private String nickname;
+
+        public ClientHandler(Socket socket) {
+            this.socket = socket;
+        }
+
+        @Override
+        public void run() {
+            try {
+                reader = new BufferedReader(new InputStreamReader(socket.getInputStream(), StandardCharsets.UTF_8));
+                writer = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream(), StandardCharsets.UTF_8));
+                requestNickname();
+                clients.add(this);
+
+                broadcast("[Сервер] " + nickname + " вошёл в чат. Участников: " + clients.size(), this);
+                send("[Сервер] " + nickname + " вошёл в чат");
+
+                String message;
+                while ((message = reader.readLine()) != null) { // null -- клиент ушел
+
+                    message = message.trim(); // удаляет пробелы переносы табуляции
+                    if (message.isEmpty()) {
+                        continue;
+                    }
+                    broadcast("[" + nickname + "] " + message, this);
+                }
+
+            } catch (IOException ignored) {
+            } finally {
+                disconnect();
+            }
+        }
+
+        private void requestNickname() throws IOException {
+            while (true) {
+                send("Введите никнейм:");
+                String input = reader.readLine();
+                if (input == null) {
+                    throw new IOException("Client disconnected before nickname");
+                }
+
+                input = input.trim();
+
+                if (!input.isEmpty()) {
+                    nickname = input;
+                    return;
+                }
+            }
+        }
+
+        private void send(String message) {
+            try {
+                writer.write(message);
+                writer.newLine();
+                writer.flush();
+            } catch (IOException ignored) {
+            }
+        }
+
+        private void disconnect() {
+            clients.remove(this);
+
+            if (nickname != null) {
+                broadcast("[Сервер] " + nickname + " покинул чат. Участников: " + clients.size(), this);
+            }
+
+            try {
+                socket.close();
+            } catch (IOException ignored) {
+            }
+        }
+    }
+}
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