using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var arr = new List<List<int>>(){new List<int>{1,2}, new List<int>{3,4}, new List<int>{5,6,7}};

        for(var j = 0; j < arr.Count; j++)

        {

            for(var i = 0; i < arr[j].Count; i++)

            {

                Console.WriteLine("i: " + i + " j:" + j);

            }

        }

    }

}