using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

    public void rotateMatrix(List<List<int>> a) {

​

        //First do the transpose of the matrix

        a = matrixTransposeWithoutUsingExtraArray(a);

​

        //Then reverse the each row of the transpose matrix

        for (int i = 0; i < a.Count; i++)

        {

            ReverseArray(a[i]);

        }

    }

​

    public void ReverseArray(List<int> A)

    {

        int i = 0, j = A.Count-1;

​

        while(i<j)

        {

            int temp = A[i];

            A[i] = A[j];

            A[j] = temp;

​

            i++;

            j--;

        }            

    }

​

    public static List<List<int>> matrixTransposeWithoutUsingExtraArray(List<List<int>> A)

    {

        int rows, cols;

        rows = A.Count;

        cols = A[0].Count;

​

        for (int i = 0; i < rows; i++)

        {

            for (int j = i + 1; j < cols; j++)

            {

                int temp = A[i][j];

                A[i][j] = A[j][i];

                A[j][i] = temp;

            }

        }

​

        return A;

    }

}