// Page 213-214

public class Line
{
	private Point startP;
	private Point endP;
	public Line()
	{
		startP = new Point();
		endP = new Point();
	}
	public Line(int sX, int sY, int eX, int eY )
	{
		startP = new Point(sX, sY);
		endP = new Point(eX, eY);
	}
	public Point startPoint()
	{
		return startP;
	}
	public Point endPoint()
	{
		return endP;
	}
	public double length()
	{
		return startP.distance(endP);
	}

	public static void main(String[] args)
	{
		Line L1 = new Line(1, 1, 0, 0);
		System.out.println(L1.length());
	}
}