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.io.IOException;
import java.util.Scanner;
public class Main {

	public static void main(String[] args) throws Exception {
		// TODO ?????????????????????????????????????????????
			Scanner sc = new Scanner(System.in);
			double a = sc.nextDouble();
			double b = sc.nextDouble();
			double c = sc.nextDouble();
			double d = sc.nextDouble();
			a -= c;
			b -= d;
			a = a*a + b*b;
			a = Math.sqrt(a);
			System.out.println(a);
	}

}