#include<iostream>
#include<cmath>
#include<iomanip>
using namespace std;
int main(){
double x1,y1,x2,y2;
cin>>x1>>y1>>x2>>y2;
cout<< setprecision(10) << sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1)) << endl;
}
### Prompt

Construct a cpp code solution to the problem outlined:

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<iostream>
#include<cmath>
#include<iomanip>
using namespace std;
int main(){
double x1,y1,x2,y2;
cin>>x1>>y1>>x2>>y2;
cout<< setprecision(10) << sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1)) << endl;
}
```