using System;
using System.Drawing;
using System.Collections.Generic;

public class Test
{
	public static void Main() {
		var list = new List<Point>();
		list.Add(new Point(10, 20));
		list.Add(new Point(20, 40));
		list.Add(new Point(40, 80));
		
		list[1].X = 30;
		
		foreach(var pt in list) {
			Console.WriteLine(pt);
		}
			
	}
}