Is it a stochastic matrix?, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            //int[,] matrix = {{100}};
            //int[,] matrix = {{42}};
            //int[,] matrix = {{100, 0}, {0, 100}};
            //int[,] matrix = { { 4, 8, 15 }, { 16, 23, 42 }, { 80, 69, 43 } };
            //int[,] matrix = {{99,1}, {2,98} };
            int[,] matrix = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}, {13, 14, 15, 16}};

Console.WriteLine(F(matrix));
        }
        
        private static int F(int[,] m)
        {
            int x, i, j, r, c, e, w;
            x = m.GetLength(0);
            e = w = 1;

for (i = 0; i < x; i++)
            {
                r = 0;
                c = 0;

for (j = 0; j < x; j++)
                {
                    r += m[i, j];
                    c += m[j, i];
                }

if (r != 100)
                    e = 0;

if (c != 100)
                    w = 0;
            }
            if (e == 1 && w == 1)
                return 3;

if (e == 1)
                return 1;

return w == 1 ? 2 : 4;
        }
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,12 sec, absolute running time: 0,08 sec, cpu time: 0,08 sec, average memory usage: 13 Mb, average nr of threads: 3