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;

class Main
{
	public static void main(String[] args){
	Scanner scan = new Scanner(System.in);
	
	double x1 = scan.nextDouble();
	double y1 = scan.nextDouble();
	double x2 = scan.nextDouble();
	double y2 = scan.nextDouble();
	
	double x = (x1 - x2) * (x1 - x2);
	double y = (y1 - y2) * (y1 - y2);
	
	double z12 = x + y;
		
	double z = Math.sqrt(z12);
	
	System.out.printf("%.8f\n", z);
	}
}