diff --git a/07-java-io/task01/src/com/example/task01/Task01Main.java b/07-java-io/task01/src/com/example/task01/Task01Main.java
index fcbd7c247..73fcd4d70 100644
--- a/07-java-io/task01/src/com/example/task01/Task01Main.java
+++ b/07-java-io/task01/src/com/example/task01/Task01Main.java
@@ -1,21 +1,32 @@
 package com.example.task01;
-
 import java.io.IOException;
 import java.io.InputStream;
-
-public class Task01Main {
-    public static void main(String[] args) throws IOException {
+public class Task01Main
+{
+    public static void main(String[] args) throws IOException
+    {
         //здесь вы можете вручную протестировать ваше решение, вызывая реализуемый метод и смотря результат
         // например вот так:
-
         /*
         System.out.println(checkSumOfStream(new ByteArrayInputStream(new byte[]{0x33, 0x45, 0x01})));
         */
-
     }
 
-    public static int checkSumOfStream(InputStream inputStream) throws IOException {
+    public static int checkSumOfStream(InputStream inputStream) throws IOException
+    {
         // your implementation here
         return 0;
+        if (inputStream == null)
+        {
+            throw new IllegalArgumentException();
+        }
+        int checkSum = 0;
+        int stream_byte = inputStream.read();
+        while (stream_byte != -1)
+        {
+            checkSum = Integer.rotateLeft(checkSum, 1) ^ stream_byte;
+            stream_byte = inputStream.read();
+        }
+        return checkSum;
     }
-}
+}
\ No newline at end of file