public static int acumArr(int[,] arr, IBinaryOperation op)
{
int res = 0;
for (int i = 0; i != arr.GetLength(0); ++i)
{
for (int j = 0; j != arr.GetLength(1); ++j)
{
res = op.accum(res, arr[i, j]);
}
}
return(res);
}