using System;

public class Program

{

    public static void Main()

    {

        int [, ] array = new int [4, 4] {{1,2,3,4}, {5,6,7,8}, {9,10,11,12}, {13,14,15,16}};

        int result = suma(array);

        Console.WriteLine("Suma Diagonal = " + result);

    }

    public static int suma(int[, ] arr){

        int sumaT = 0;

        for (int i = 0; i < arr.GetLength(0); i++)

        {

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

            {

                sumaT += arr[i, j];

            }

        }

        return sumaT;

    } 

}