ElemBeamsSum

class Program
    {
        static int ElemBeamsSum(int[,] arr, int x, int y, int len)
        {
            int i1 = x - y >= 0 ? x - y : 0,
                j1 = i1 == 0 ? y - x : 0,
                i1_stop = x >= y ? len - 1 : (len - 1) - y + x,
                j1_stop = x <= y ? len - 1 : (len - 1) - x + y,
                i2 = x + y >= len - 1 ? len - 1 : x + y,
                j2 = x + y <= len - 1 ? 0 : x + y - (len - 1),
                i2_stop = j2,
                j2_stop = i2,
                sum = 0;
            while (i1 <= i1_stop && j1 <= j1_stop || i2 >= i2_stop && j2 <= j2_stop)
            {
                if (i1 <= i1_stop && j1 <= j1_stop)
                {
                    sum += arr[i1, j1];
                    i1++; j1++;
                }
                if (i2 >= i2_stop && j2 <= j2_stop)
                {
                    sum += arr[i2, j2];
                    i2--;
                    j2++;
                }
            }
            return x == 0 || y == 0 || x == len - 1 || y == len - 1 ? sum - arr[x, y] : sum;

        }
        static void Main(string[] args)
        {
            int[,] arr = {
            { 1, 1, 2, 3, 4 },
            { 1, 1, 1, 1, 1 },
            { 2, 1, 2, 1, 2 },
            { 3, 1, 1, 3, 3 },
            { 4, 1, 2, 3, 4 },
            };
            Console.WriteLine(ElemBeamsSum(arr, 0, 1, 5));
        }
    }