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;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);
		double x1 = sc.nextDouble();
		double y1 = sc.nextDouble();
		double x2 = sc.nextDouble();
		double y2 = sc.nextDouble();

		System.out.println(Math.sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)));
	}

}