using System;
using System.Collections.Generic;
public class Program
{
public static void Main()
List<int> a = new List<int>();
List<int> b = new List<int>();
Change(a, ref b);
Console.WriteLine(a.Count);
Console.WriteLine(b.Count);
}
public static void Change (List<int> first, ref List<int> second)
first.Add(1);
first.Add(2);
second.Add(3);
second.Add(4);
first = null;
second = null;