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;
import java.lang.Math;
public class Main {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		double a = Double.parseDouble(scan.next());
		double b = Double.parseDouble(scan.next());
		double c = Double.parseDouble(scan.next());
		double d = Double.parseDouble(scan.next());
		System.out.println(String.format("%6f",Math.sqrt((c-a)*(c-a)+(d-b)*(d-b))));
	}

}