diff --git a/task01/src/com/example/task01/Task01Main.java b/task01/src/com/example/task01/Task01Main.java
index 7efef9a8..b4e22012 100644
--- a/task01/src/com/example/task01/Task01Main.java
+++ b/task01/src/com/example/task01/Task01Main.java
@@ -15,7 +15,19 @@ public static void main(String[] args) throws IOException {
     }
 
     public static int checkSumOfStream(InputStream inputStream) throws IOException {
-        // your implementation here
-        return 0;
+
+        if (inputStream == null) {
+            throw new IllegalArgumentException();
+        }
+
+        int result = 0;
+        int b, c;
+
+        while ((b = inputStream.read()) != -1) {
+            c = Integer.rotateLeft(result, 1);
+            result = c ^ b;
+        }
+
+        return result;
     }
-}
+}
\ No newline at end of file
diff --git a/task02/src/com/example/task02/Task02Main.java b/task02/src/com/example/task02/Task02Main.java
index 865ea659..e872ef35 100644
--- a/task02/src/com/example/task02/Task02Main.java
+++ b/task02/src/com/example/task02/Task02Main.java
@@ -9,5 +9,24 @@ public static void main(String[] args) throws IOException {
         // - направить стандартный вывод программы в файл output.test
         // - запустить программу
         // - и сравнить получившийся файл output.test с expected.test
+
+        int currentByte;
+        int nextByte;
+
+        currentByte = System.in.read();
+
+        while (currentByte != -1) {
+            nextByte = System.in.read();
+
+            if (currentByte == 13 && nextByte == 10) {
+                currentByte = nextByte;
+                continue;
+            }
+
+            System.out.write(currentByte);
+
+            currentByte = nextByte;
+        }
+        System.out.flush();
     }
 }
diff --git a/task03/src/com/example/task03/Task03Main.java b/task03/src/com/example/task03/Task03Main.java
index 332e0366..00a113fc 100644
--- a/task03/src/com/example/task03/Task03Main.java
+++ b/task03/src/com/example/task03/Task03Main.java
@@ -2,6 +2,7 @@
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.InputStreamReader;
 import java.nio.charset.Charset;
 
 public class Task03Main {
@@ -15,7 +16,15 @@ public static void main(String[] args) throws IOException {
     }
 
     public static String readAsString(InputStream inputStream, Charset charset) throws IOException {
-        // your implementation here
-        return "";
+        if (inputStream == null || charset == null) {
+            throw new IllegalArgumentException();
+        }
+        InputStreamReader reader = new InputStreamReader(inputStream, charset);
+        StringBuilder result = new StringBuilder();
+        int c;
+        while ((c = reader.read()) != -1) {
+            result.append((char) c);
+        }
+        return result.toString();
     }
 }
diff --git a/task04/src/com/example/task04/Task04Main.java b/task04/src/com/example/task04/Task04Main.java
index 4236c2e7..6c74834c 100644
--- a/task04/src/com/example/task04/Task04Main.java
+++ b/task04/src/com/example/task04/Task04Main.java
@@ -1,6 +1,8 @@
 package com.example.task04;
 
 import java.io.IOException;
+import java.util.Locale;
+import java.util.Scanner;
 
 public class Task04Main {
     public static void main(String[] args) throws IOException {
@@ -9,6 +11,14 @@ public static void main(String[] args) throws IOException {
         // - запустить программу
         // - проверить, что получилось 351.731900
 
-        System.out.println("0.0");
+        Scanner scanner = new Scanner(System.in).useLocale(Locale.US);
+        double result = 0;
+
+        while (scanner.hasNextDouble()) {
+            double token = scanner.nextDouble();
+            result += token;
+        }
+
+        System.out.printf(Locale.US,"%.6f", result);
     }
-}
+}
\ No newline at end of file