using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Random rand = new Random();

        var x = 10; var y = 10; var maxNumber = 20;

        var matrix = new int[x,y];

        for(int i =0; i<x;i++){

            for(int i2 =0; i2<y;i2++){

                matrix[i, i2] = rand.Next(maxNumber);

            }   

        }

        var list = GetElementsBelowDiagonal(matrix);

        foreach(var item in list){

            Console.Write(item + "+");

        }

        Console.Write("/"+list.Count);

    }

    private static List<int> GetElementsBelowDiagonal(int[,] matrix) 

    { 

        List<int> elementsBelowDiagonal = new List<int>(); 

        for (int i = 1; i < matrix.GetLength(0); i++) { 

            for (int j = 0; j < i; j++) { 

                elementsBelowDiagonal.Add(matrix[i, j]); 

                //Console.Write(matrix[i, j] + " "); 

            } 

        } 

        return elementsBelowDiagonal; 

    }

}