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;

public class Main {
	public static void main(String[] args) {
		Scanner scn = new Scanner(System.in);
		double x1 = scn.nextDouble();
		double y1 = scn.nextDouble();
		double x2 = scn.nextDouble();
		double y2 = scn.nextDouble();
		double a = (x2 - x1) * (x2 - x1);
		double b = (y2 - y1) * (y2 - y1);
		System.out.println(Math.sqrt(a + b));
	}
}