diff --git a/Java_4.java b/Java_4.java
index 8b13789..54dcb01 100644
--- a/Java_4.java
+++ b/Java_4.java
@@ -1 +1,118 @@
+/**
+ * Java 1. Lesson 4. Tic-tac-toe in console
+ *
+ * @author Rudenko Alexandr
+ * @version dated  01/12/2018
+ */
+import java.util.Random;
+import java.util.Scanner;
 
+class TicTacToe {
+
+    final int SIZE = 3;
+    final char DOT_X = 'x';
+    final char DOT_O = 'o';
+    final char DOT_EMPTY = '.';
+    char[][] map = new char[SIZE][SIZE];
+    Scanner sc = new Scanner(System.in);
+    Random rand = new Random();
+
+    public static void main(String[] args) {
+        new TicTacToe().game();
+    }
+
+    void game() {
+        initMap();
+        while (true) {
+            humanTurn();
+            if (checkWin(DOT_X)) {
+                System.out.println("YOU WON!");
+                break;
+            }
+            if (isMapFull()) {
+                System.out.println("Sorry, DRAW!");
+                break;
+            }
+            aiTurn();
+            printMap();
+            if (checkWin(DOT_O)) {
+                System.out.println("AI WON!");
+                break;
+            }
+            if (isMapFull()) {
+                System.out.println("Sorry, DRAW!");
+                break;
+            }
+        }
+        System.out.println("GAME OVER.");
+        printMap();
+    }
+
+    void initMap() {
+        for (int i = 0; i < SIZE; i++)
+            for (int j = 0; j < SIZE; j++)
+                map[i][j] = DOT_EMPTY;
+    }
+
+    void printMap() {
+        for (int i = 0; i < SIZE; i++) {
+            for (int j = 0; j < SIZE; j++)
+                System.out.print(map[i][j] + " ");
+            System.out.println();
+        }
+        System.out.println();
+    }
+
+    void humanTurn() {
+        int x, y;
+        do {
+            System.out.println("Enter X and Y (1..3):");
+            x = sc.nextInt() - 1;
+            y = sc.nextInt() - 1;
+        } while (!isCellValid(x, y));
+        map[y][x] = DOT_X;
+    }
+
+    void aiTurn() {
+        int x, y;
+        do {
+            x = rand.nextInt(SIZE);
+            y = rand.nextInt(SIZE);
+        } while (!isCellValid(x, y));
+        map[y][x] = DOT_O;
+    }
+
+    boolean checkWin(char dot) {
+        // check horizontals, verticals, diagonals
+       
+        for (int i = 0; i < 1; i++) {
+            for (int j = 0; j < 1; j++)
+                if ( (map[i][j] == dot && map[i][j+1] == dot && map[i][j+2] == dot) ||
+                      (map[i+1][j] == dot && map[i+1][j+1] == dot && map[i+1][j+2] == dot) ||
+                       (map[i+2][j] == dot && map[i+2][j+1] == dot && map[i+1][j+2] == dot) ||
+                     (map[i][j] == dot && map[i+1][j] == dot && map[i+2][j] == dot) ||
+                        (map[i][j+1] == dot && map[i+1][j+1] == dot && map[i+2][j+1] == dot) ||
+                        (map[i][j+2] == dot && map[i+1][j+2] == dot && map[i+2][j+2] == dot) ||
+                     (map[i][j] == dot && map[i+1][j+1] == dot && map[i+2][j+2] == dot) ||
+                        (map[i+2][j] == dot && map[i+1][j+1] == dot && map[i][j+2] == dot)
+                )
+                   return true;
+        }
+       
+        return false;
+    }
+
+    boolean isMapFull() {
+        for (int i = 0; i < SIZE; i++)
+            for (int j = 0; j < SIZE; j++)
+                if (map[i][j] == DOT_EMPTY)
+                    return false;
+        return true;
+    }
+
+    boolean isCellValid(int x, int y) {
+        if (x < 0 || y < 0 || x >= SIZE || y >= SIZE)
+            return false;
+        return map[y][x] == DOT_EMPTY; // by DSerov
+    }
+}