diff --git a/task01/src/com/example/task01/Task01Main.java b/task01/src/com/example/task01/Task01Main.java
index de4599c1..431b8ece 100644
--- a/task01/src/com/example/task01/Task01Main.java
+++ b/task01/src/com/example/task01/Task01Main.java
@@ -23,7 +23,11 @@ public static <T, U> Function<T, U> ternaryOperator(
             Function<? super T, ? extends U> ifTrue,
             Function<? super T, ? extends U> ifFalse) {
 
-        return null; // your implementation here
+        if (condition == null || ifTrue == null || ifFalse == null) {
+            throw new NullPointerException();
+        }
 
+        return t -> condition.test(t) ? ifTrue.apply(t) : ifFalse.apply(t);
     }
+
 }
diff --git a/task02/src/com/example/task02/Task02Main.java b/task02/src/com/example/task02/Task02Main.java
index 309260d8..8946f1e6 100644
--- a/task02/src/com/example/task02/Task02Main.java
+++ b/task02/src/com/example/task02/Task02Main.java
@@ -1,22 +1,27 @@
 package com.example.task02;
 
 import java.util.stream.IntStream;
+import java.util.stream.Stream;
 
 public class Task02Main {
 
     public static void main(String[] args) {
 
-        /*
-        cycleGrayCode(2)
+
+        cycleGrayCode(3)
                 .limit(10)
                 .forEach(System.out::println);
-        */
+
 
     }
 
     public static IntStream cycleGrayCode(int n) {
 
-        return null; // your implementation here
+        if (n > 16 || n < 1){
+            throw new IllegalArgumentException();
+        }
+        return IntStream.iterate(0, t -> (t + 1) % (int)Math.pow(2, n)
+                ).map(f -> f ^ (f >> 1)); // your implementation here
 
     }
 
diff --git a/task03/src/com/example/task03/Task03Main.java b/task03/src/com/example/task03/Task03Main.java
index 254d5cb0..5b79c72b 100644
--- a/task03/src/com/example/task03/Task03Main.java
+++ b/task03/src/com/example/task03/Task03Main.java
@@ -1,7 +1,11 @@
 package com.example.task03;
 
 import java.util.Comparator;
+import java.util.Iterator;
+import java.util.List;
+import java.util.TreeSet;
 import java.util.function.BiConsumer;
+import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 public class Task03Main {
@@ -21,7 +25,29 @@ public static <T> void findMinMax(
             Stream<? extends T> stream,
             Comparator<? super T> order,
             BiConsumer<? super T, ? super T> minMaxConsumer) {
+        if (stream == null || order == null || minMaxConsumer == null) {
+            throw new NullPointerException();
+        }
 
-        // your implementation here
+        Iterator<? extends T> iterator = stream.iterator();
+
+        T maxElement = null;
+        T minElement = null;
+
+        if(iterator.hasNext())
+        {   T firstElement = iterator.next();
+            maxElement = firstElement;
+            minElement = firstElement;
+        }
+
+        while (iterator.hasNext()){
+            T currentElement = iterator.next();
+            if (order.compare(currentElement,maxElement)>0)
+                maxElement = currentElement;
+            if (order.compare(currentElement,minElement)<0)
+                minElement = currentElement;
+        }
+
+        minMaxConsumer.accept(minElement,maxElement);
     }
 }
diff --git a/task04/src/com/example/task04/Task04Main.java b/task04/src/com/example/task04/Task04Main.java
index 1e38e6eb..6913e108 100644
--- a/task04/src/com/example/task04/Task04Main.java
+++ b/task04/src/com/example/task04/Task04Main.java
@@ -1,10 +1,31 @@
 package com.example.task04;
 
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.util.Comparator;
+import java.util.Map;
+import java.util.function.ToLongFunction;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
 public class Task04Main {
 
     public static void main(String[] args) {
 
-        // your implementation here
+        BufferedReader reader = new BufferedReader( new InputStreamReader(System.in));
+
+        reader.lines()
+                .map(String::toLowerCase)
+                .flatMap(x -> Stream.of(x.split("[^a-zа-яё0-9]")))
+                .filter(x -> !x.isEmpty())
+                .collect(Collectors.groupingBy(x -> x, Collectors.counting()))
+                .entrySet()
+                .stream()
+                .sorted(Comparator.comparingLong((ToLongFunction<Map.Entry<String,Long>>) Map.Entry::getValue)
+                        .reversed()
+                        .thenComparing(Map.Entry::getKey))
+                .limit(10)
+                .forEach(t -> System.out.print(t.getKey() + "\n"));
 
     }
 
diff --git a/task05/src/com/example/task05/InfoKeeper.java b/task05/src/com/example/task05/InfoKeeper.java
new file mode 100644
index 00000000..5c205044
--- /dev/null
+++ b/task05/src/com/example/task05/InfoKeeper.java
@@ -0,0 +1,26 @@
+package com.example.task05;
+
+public class InfoKeeper<T> {
+    private String from;
+    private String to;
+    private T content;
+
+    public InfoKeeper(String from, String to, T content){
+        this.from = from;
+        this.to = to;
+        this.content = content;
+    }
+
+    public String getFrom() {
+        return from;
+    }
+
+    public String getTo() {
+        return to;
+    }
+
+    public T getContent() {
+        return content;
+    }
+
+}
diff --git a/task05/src/com/example/task05/MailMessage.java b/task05/src/com/example/task05/MailMessage.java
new file mode 100644
index 00000000..442427dd
--- /dev/null
+++ b/task05/src/com/example/task05/MailMessage.java
@@ -0,0 +1,7 @@
+package com.example.task05;
+
+public class MailMessage extends InfoKeeper<String>{
+    public MailMessage(String to, String from, String content){
+        super(to, from, content);
+    }
+}
diff --git a/task05/src/com/example/task05/MailService.java b/task05/src/com/example/task05/MailService.java
new file mode 100644
index 00000000..007d856f
--- /dev/null
+++ b/task05/src/com/example/task05/MailService.java
@@ -0,0 +1,23 @@
+package com.example.task05;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Consumer;
+public class MailService<T> implements Consumer<InfoKeeper<T>> {
+    private final Map<String, List<T>> MailBox = new HashMap<String, List<T>>(){
+        @Override
+        public List<T> get(Object key) {
+            List<T> list = super.get(key);
+            return list != null ? list : new ArrayList<>();
+        }
+    };
+    public Map<String, List<T>> getMailBox() {
+        return MailBox;
+    }
+    @Override
+    public void accept(InfoKeeper<T> keeper) {
+        MailBox.computeIfAbsent(keeper.getTo(), k -> new ArrayList<>())
+                .add(keeper.getContent());
+    }
+}
diff --git a/task05/src/com/example/task05/Salary.java b/task05/src/com/example/task05/Salary.java
new file mode 100644
index 00000000..31acdc50
--- /dev/null
+++ b/task05/src/com/example/task05/Salary.java
@@ -0,0 +1,7 @@
+package com.example.task05;
+
+public class Salary extends InfoKeeper<Integer>{
+    public Salary(String to, String from, Integer content){
+        super(to, from, content);
+    }
+}
diff --git a/task05/src/com/example/task05/Task05Main.java b/task05/src/com/example/task05/Task05Main.java
index ae31f6bc..065eadf3 100644
--- a/task05/src/com/example/task05/Task05Main.java
+++ b/task05/src/com/example/task05/Task05Main.java
@@ -9,7 +9,7 @@ public class Task05Main {
 
     public static void main(String[] args) {
 
-        /*
+
 
         // Random variables
         String randomFrom = "..."; // Некоторая случайная строка. Можете выбрать ее самостоятельно.
@@ -88,7 +88,7 @@ public static void main(String[] args) {
         assert salaries.get(randomTo).equals(Arrays.asList(randomSalary)) : "wrong salaries mailbox content (3)";
 
 
-        */
+
 
     }