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.*;
public class Main{

    public static void main(String[] args){

        Scanner sc = new Scanner(System.in);

        double x1 = sc.nextDouble();
        double y1 = sc.nextDouble();
        double x2 = sc.nextDouble();
        double y2 = sc.nextDouble();
        
        //三平方の定理
        System.out.println(Math.sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1)));

    }

}