using System;

public class Program

{

    public static bool IsToeplitzMatrix(int[][] matrix) 

    {

        int n = matrix.Length;

        int m = matrix[0].Length;

​

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

        {

            for (int j = 0; j < m; j++)

            {

                if (i > 0 && j > 0 && matrix[i - 1][j - 1] != matrix[i][j])

                    return false;

            }

        }

​

        return true;

    }

    public static void Main()

    {

        Console.WriteLine("UniLecs");

        // tests

        var matrix = new int[][] {

            new int[] { 1, 2, 3, 4 },

            new int[] { 5, 1, 2, 3 },

            new int[] { 9, 5, 1, 2 }

        };

        Console.WriteLine(IsToeplitzMatrix(matrix).ToString()); // true

    }

}