diff --git a/Lab4/Program.cs b/Lab4/Program.cs
index 59898f2..8ceb9f4 100644
--- a/Lab4/Program.cs
+++ b/Lab4/Program.cs
@@ -4,6 +4,8 @@ public class Program
     {
         public static void Main()
         {
+            
         }
     }
 }
+
diff --git a/Lab4/Purple.cs b/Lab4/Purple.cs
index cb4bd6a..0909a8e 100644
--- a/Lab4/Purple.cs
+++ b/Lab4/Purple.cs
@@ -117,4 +117,4 @@ public void Task10(int[] array, int N)
             return (bright, normal, dim);
         }
     }
-}
\ No newline at end of file
+ }
diff --git a/Lab4/White.cs b/Lab4/White.cs
index d39815d..98812c9 100644
--- a/Lab4/White.cs
+++ b/Lab4/White.cs
@@ -1,5 +1,4 @@
-namespace Lab4
-{
+
     public class White
     {
         public double Task1(int[] vector)
@@ -7,97 +6,179 @@ public double Task1(int[] vector)
             double length = 0;
 
             // code here
-
+            if (vector == null || vector.Length == 0) return 0;
+            double sum = 0;
+            foreach (int x in vector)
+                sum += x * x;
+            length = Math.Sqrt(sum);
             // end
-
             return length;
         }
         public int Task2(int[] array, int P, int Q)
         {
             int count = 0;
-
             // code here
-
+            if (array == null || array.Length == 0) return 0;
+            int min = Math.Min(P, Q);
+            int max = Math.Max(P, Q);
+            foreach (int x in array)
+                if (x > min && x < max)
+                    count++;
             // end
 
             return count;
         }
+
         public void Task3(int[] array)
         {
-
             // code here
+            if (array == null || array.Length == 0) return;
+            int maxIndex = 0;
+            for (int i = 1; i < array.Length; i++)
+                if (array[i] > array[maxIndex]) maxIndex = i;
 
-            // end
+            if (maxIndex == array.Length - 1) return;
 
+            int minAfterIndex = maxIndex + 1;
+            for (int i = maxIndex + 1; i < array.Length; i++)
+                if (array[i] < array[minAfterIndex]) minAfterIndex = i;
+
+            if (array[minAfterIndex] == array[maxIndex]) return;
+
+            int temp = array[maxIndex];
+            array[maxIndex] = array[minAfterIndex];
+            array[minAfterIndex] = temp;
+            // end
         }
+
         public void Task4(int[] array)
         {
-
             // code here
-
+            if (array == null || array.Length == 0) return;
+            int maxIndex = -1;
+            int maxVal = int.MinValue;
+            for (int i = 0; i < array.Length; i += 2)
+            {
+                if (array[i] > maxVal)
+                {
+                    maxVal = array[i];
+                    maxIndex = i;
+                }
+            }
+            if (maxIndex != -1)
+                array[maxIndex] = maxIndex;
             // end
 
         }
+
         public int Task5(int[] array, int P)
         {
             int index = 0;
 
             // code here
-
+            if (array == null || array.Length == 0) return -1;
+            index = Array.IndexOf(array, P);
             // end
 
             return index;
         }
+
         public void Task6(int[] array)
         {
 
             // code here
-
+            if (array == null || array.Length < 2) return;
+            int maxIndex = 0;
+            for (int i = 1; i < array.Length; i++)
+                if (array[i] > array[maxIndex]) maxIndex = i;
+
+            if (maxIndex == 0) return;
+
+            for (int i = 0; i + 1 < maxIndex; i += 2)
+            {
+                int temp = array[i];
+                array[i] = array[i + 1];
+                array[i + 1] = temp;
+            }
             // end
 
         }
+
         public int[] Task7(int[] array)
         {
             int[] answer = null;
 
             // code here
-
+            if (array == null) return null;
+            answer = array.Where(x => x >= 0).ToArray();
             // end
 
             return answer;
         }
+
         public void Task8(int[] array)
         {
 
             // code here
-
+            if (array == null || array.Length <= 1) return;
+            Array.Sort(array);
+            Array.Reverse(array);
             // end
 
         }
+
         public void Task9(int[] array)
         {
 
             // code here
-
+            if (array == null || array.Length <= 1) return;
+            Array.Reverse(array);
             // end
-
+            
         }
+
         public int[] Task10(int[] A, int[] B)
         {
             int[] C = null;
 
             // code here
-
+            if (A == null && B == null) return null;
+            if (A == null || A.Length == 0) return (int[])B.Clone();
+            if (B == null || B.Length == 0) return (int[])A.Clone();
+
+            int len = A.Length + B.Length;
+            C = new int[len];
+            int i = 0, j = 0, k = 0;
+
+            while (i < A.Length && j < B.Length)
+            {
+                C[k++] = A[i++];
+                C[k++] = B[j++];
+            }
+            while (i < A.Length) C[k++] = A[i++];
+            while (j < B.Length) C[k++] = B[j++];
             // end
 
             return C;
         }
+
         public double[] Task11(double a, double b, int n)
         {
             double[] array = null;
 
             // code here
-
+            if (n <= 0) return null;
+            if (a == b && n == 1)
+            {
+                array = new double[] { a };
+                return array;
+            }
+            if (a == b || n < 2) return null;
+
+            array = new double[n];
+            double step = (b - a) / (n - 1);
+            for (int i = 0; i < n; i++)
+                array[i] = a + i * step;
             // end
 
             return array;
@@ -108,10 +189,27 @@ public double[] Task12(double[] raw)
             double[] restored = null;
 
             // code here
-
+            if (raw == null || raw.Length < 3) return null;
+            if (raw.All(x => x == -1)) return (double[])raw.Clone();
+
+            restored = (double[])raw.Clone();
+            for (int i = 0; i < raw.Length; i++)
+            {
+                if (raw[i] == -1)
+                {
+                    double left = (i > 0) ? raw[i - 1] : -1;
+                    double right = (i < raw.Length - 1) ? raw[i + 1] : -1;
+
+                    if (left != -1 && right != -1)
+                        restored[i] = (left + right) / 2;
+                    else if (left != -1 && right == -1)
+                        restored[i] = left;
+                    else if (left == -1 && right != -1)
+                        restored[i] = right;
+                }
+            }
             // end
-
             return restored;
         }
     }
-}
\ No newline at end of file
+