Problem: Write a program which calculates the distance between two points P1(x1, y1) and P2(x2, y2).



Input

Four real numbers x1, y1, x2 and y2 are given in a line.

Output

Print the distance in real number. The output should not contain an absolute error greater than 10-4.

Example

Input

0 0 1 1


Output

1.41421356

Solution (in JAVA):

Solution:
import java.util.Scanner;
import java.awt.geom.Point2D;
import java.text.DecimalFormat;
class Main{
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		while(sc.hasNext()){
			DecimalFormat frt = new DecimalFormat("0.0000000");
			Point2D.Double point = new Point2D.Double();
			System.out.println(frt.format(point.distance(sc.nextDouble(),sc.nextDouble(),sc.nextDouble(),sc.nextDouble())));
		}
	}
}