diff --git a/src/main/java/school/lemon/changerequest/java/introduction/pr1/Bob.java b/src/main/java/school/lemon/changerequest/java/introduction/pr1/Bob.java
index e8c7aec..8dc35d9 100644
--- a/src/main/java/school/lemon/changerequest/java/introduction/pr1/Bob.java
+++ b/src/main/java/school/lemon/changerequest/java/introduction/pr1/Bob.java
@@ -4,7 +4,19 @@
 public class Bob {
 
     public static String hey(String phrase) {
-        return "";
+
+        if (phrase.trim().isEmpty()) {
+            return "Fine.";
+        }
+
+        if (phrase.equals(phrase.toUpperCase()) && !phrase.equals(phrase.toLowerCase())) {
+            return "Chill out!";
+        }
+
+        if (phrase.endsWith("?")) {
+            return "Yeap.";
+        }
+        else return "Whatever.";
     }
 
 }
diff --git a/src/main/java/school/lemon/changerequest/java/introduction/pr1/ConsoleCalculator.java b/src/main/java/school/lemon/changerequest/java/introduction/pr1/ConsoleCalculator.java
index da96e86..2b1e006 100644
--- a/src/main/java/school/lemon/changerequest/java/introduction/pr1/ConsoleCalculator.java
+++ b/src/main/java/school/lemon/changerequest/java/introduction/pr1/ConsoleCalculator.java
@@ -1,9 +1,71 @@
 package school.lemon.changerequest.java.introduction.pr1;
 
 
+import java.util.Scanner;
+
 public class ConsoleCalculator {
 
     public static void main(String[] args) {
 
+        Scanner scanner = new Scanner(System.in);
+        makeChoice();
+        String input;
+        int a, b;
+        while (true) {
+            while (!scanner.hasNext("(exit|help|add|sub|mul|div)")) {
+                System.out.println("False, please try again.");
+                makeChoice();
+                scanner.next();
+            }
+            input = scanner.next();
+
+            if (input.equals("exit")) {
+                System.out.println("Bye-bye");
+                scanner.close();
+                break;
+            }
+            if (input.equals("help")) {
+                makeChoice();
+                scanner.next();
+            }
+
+            System.out.println("Enter first number:");
+            a = scanner.nextInt();
+            System.out.println("Enter second number:");
+            b = scanner.nextInt();
+
+            switch (input) {
+                case "add":
+                    int sum = a + b;
+                    System.out.println(a + "+" + b + "= " + sum);
+                    break;
+                case "sub":
+                    int sub = a - b;
+                    System.out.println(a + "-" + b + "= " + sub);
+                    break;
+                case "mul":
+                    int mul = a * b;
+                    System.out.println(a + "*" + b + "= " + mul);
+                    break;
+                case "div":
+                    int div = a / b;
+                    System.out.println(a + "/" + b + "= " + div);
+                    break;
+                }
+            makeChoice();
+        }
+
+    }
+
+    private static void makeChoice () {
+        System.out.println("Console calculator");
+        System.out.println("Enter 'add' to perform addition.");
+        System.out.println("Enter 'sub' to perform subtraction.");
+        System.out.println("Enter 'mul' to perform multiplication.");
+        System.out.println("Enter 'div' to perform division.");
+        System.out.println("Enter 'exit' to exit.");
+        System.out.println("Enter 'help' to see help message.");
+        System.out.println("Make your choice.");
+
     }
 }
diff --git a/src/main/java/school/lemon/changerequest/java/introduction/pr1/HammingDistance.java b/src/main/java/school/lemon/changerequest/java/introduction/pr1/HammingDistance.java
index b8a218f..96ba0bd 100644
--- a/src/main/java/school/lemon/changerequest/java/introduction/pr1/HammingDistance.java
+++ b/src/main/java/school/lemon/changerequest/java/introduction/pr1/HammingDistance.java
@@ -2,6 +2,15 @@
 
 public class HammingDistance {
     public static int compute(String a, String a1) {
-        return -1;
+
+        if (a.length() != a1.length()) return -1;
+
+        int result = 0;
+        for (int i = 0; i < a.length(); i++) {
+            if (a.charAt(i) != a1.charAt(i)) {
+                return result++;
+            }
+        }
+        return result;
     }
 }