#include <bits/stdc++.h>
using namespace std;

int main(){
double x1,y1,x2,y2;
cin>>x1>>y1>>x2>>y2;
double d;
d=sqrt(x1*x1+y1*y1+x2*x2+y2*y2-2*x1*x2-2*y1*y2);
cout << fixed << setprecision(10);
cout<<d<<endl;
}

### Prompt

Your task is to create 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(){
double x1,y1,x2,y2;
cin>>x1>>y1>>x2>>y2;
double d;
d=sqrt(x1*x1+y1*y1+x2*x2+y2*y2-2*x1*x2-2*y1*y2);
cout << fixed << setprecision(10);
cout<<d<<endl;
}

```