#include<bits/stdc++.h>
using namespace std;
int main(void){
	double x1,y1,x2,y2;
	double x;
	
	cin>>x1>>y1>>x2>>y2;
	x=sqrt(pow(x2-x1,2)+pow(y2-y1,2));
	cout<<fixed;
	cout<<x<<endl;
	return 0;
}

### Prompt

Your challenge is to write a CPP solution to the following 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

### Response

```cpp
#include<bits/stdc++.h>
using namespace std;
int main(void){
	double x1,y1,x2,y2;
	double x;
	
	cin>>x1>>y1>>x2>>y2;
	x=sqrt(pow(x2-x1,2)+pow(y2-y1,2));
	cout<<fixed;
	cout<<x<<endl;
	return 0;
}

```