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) {
		// TODO ?????????????????????????????????????????????
Scanner kb=new Scanner(System.in);
double x1=kb.nextDouble();
double y1=kb.nextDouble();
double x2=kb.nextDouble();
double y2=kb.nextDouble();
double xd=x2-x1;
double yd=y2-y1;

System.out.printf(
		"%f\n",Math.sqrt(xd*xd+yd*yd));
	}

}