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 p[] = new double[4];
		int i=0;
		double dx,dy;
		
		for(i = 0;i<4;i++){
			p[i]=sc.nextDouble();
		}
		
		dx = Math.pow((p[0]-p[2]), 2.0);
		dy = Math.pow((p[1]-p[3]), 2.0);
		
		System.out.printf("%.8f\n", Math.sqrt((dx+dy)));
	}

}