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