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 CPP):

Solution:
#include<iostream>
#include<math.h>
#include<cstdio>
using namespace std;
int main(){
	double x1,x2,y1,y2,ans1;
	cin>>x1>>y1>>x2>>y2;
		ans1=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
		printf("%.9f\n",ans1);
	return 0;
}