diff --git a/.idea/misc.xml b/.idea/misc.xml
index a165cb3..d5d79e0 100644
--- a/.idea/misc.xml
+++ b/.idea/misc.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
-  <component name="ProjectRootManager" version="2" default="false" project-jdk-type="JavaSDK">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_8" default="false" project-jdk-name="1.8" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/out" />
   </component>
 </project>
\ No newline at end of file
diff --git a/src/repl/Main.java b/src/repl/Main.java
index 625a751..473a1c6 100644
--- a/src/repl/Main.java
+++ b/src/repl/Main.java
@@ -1,7 +1,25 @@
 package repl;
 
+import java.util.Scanner;
+
 public class Main {
     public static void main(String[] args) {
-        System.out.print("Hello world!");
+        Scanner in = new Scanner(System.in);
+        while (true) {
+            String s = in.nextLine();
+            if (s.equals("/exit")) {
+                System.out.println("Buy!");
+                return;
+            } else if (s.equals("/help")) {
+                System.out.println("The program calculates the sum of numbers");
+            } else {
+                String[] ary = s.split(" ");
+                int result = 0;
+                for (String num : ary) {
+                    result += Integer.parseInt(num);
+                }
+                System.out.println(result);
+            }
+        }
     }
 }
\ No newline at end of file