public static Coordinate toCoordinate(string rhs)
		{
			string[] sub_strings = rhs.Split(',');
			int _x, _y;
			int.TryParse (sub_strings[0],out _x);
			int.TryParse (sub_strings[1],out _y);
			Coordinate result = new Coordinate(_x, _y); 
			return result;
		}
		public static Coordinate operator-(Coordinate rhs)
		{
			Coordinate result = new Coordinate (-rhs.x, -rhs.y);
			return result;
		}
		public Coordinate(Coordinate rhs) {x=rhs.x; y=rhs.y;}
		public static Coordinate operator-(Coordinate lhs, Coordinate rhs)
		{
			Coordinate result = new Coordinate (lhs.x - rhs.x, lhs.y - rhs.y);
			return result;
		}
		public bool Equals(Coordinate rhs)
		{
			// Return true if the fields match:
			return (x == rhs.x) && (y == rhs.y);
		}