using System;
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);
		}
	}
 
	class Point {
 
		public int X { get; set; }
		public int Y { get; set; }
 
		public Point(int x, int y) {
			X = x;
			Y = y;
		}
 
		public override String ToString() {
			return String.Format("X = {0}, Y = {1}", X, Y);
		}
	}
}

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