2-Dimensional Array

using System;

namespace _2DimensionalArray
{
    class Program
    {
        static void Main(string[] args)
        {
            int[,] A = new int[100,100];
            int i, j;
            int n, m;
            Console.Write("Input the number of the row: ");
            n = int.Parse(Console.ReadLine());
            Console.Write("Input the number of the column: ");
            m = int.Parse(Console.ReadLine());
            for (i = 1; i <= n; i++)
                for (j = 1; j <= m; j++)
                {
                    Console.Write("A[{0},{0}]: = ", i, j);
                    A[i, j] = int.Parse(Console.ReadLine());
                }
            for (i = 1; i <= n; i++)
            {
                for (j = 1; j <= m; j++)
                    Console.Write("{0} ", A[i, j]);
                Console.WriteLine();
            }
            Console.ReadLine();
            int S = 0, S2 = 0;
            for (i = 1; i <= n; i++)
            {
                S = S + A[i, i];
                S2 = S2 + A[i, n - i + 1];
            }
            Console.WriteLine("Sum of the first diagram: {0}", S);
            Console.Write("Sum of the second diagram: {0}", S2);
            Console.ReadLine();
        }
    }
}