Write a C# program to calculate the sum of all the integers of a rectangular matrix except those integers which are located below an intger of value 0

using System;
public class Example
{
       public static int sum_matrix_elements(int[][] my_matrix)
        {
            int x = 0;
            for (int i = 0; i < my_matrix[0].Length; i++)
                for (int j = 0; j < my_matrix.Length && my_matrix[j][i] > 0; j++)
                    x += my_matrix[j][i];

            return x;
        }
        
      public static void Main()
        {
            Console.WriteLine(sum_matrix_elements(
                new int[][] {
                    new int[]{0, 2, 3, 2},
                    new int[]{0, 6, 0, 1},
                    new int[]{4, 0, 3, 0}
                }));
            Console.WriteLine(sum_matrix_elements(
                new int[][] {
                    new int[]{1, 2, 1, 0 },
                    new int[]{0, 5, 0, 0},
                    new int[]{1, 1, 3, 10 }
                }));
            Console.WriteLine(sum_matrix_elements(
                new int[][] {
                    new int[]{1, 1},
                    new int[]{2, 2},
                    new int[]{3, 3},
                    new int[]{4, 4}
                }));
    }
}