#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
int main()
{
  double x1,y1,x2,y2;
  cin>>x1>>y1>>x2>>y2;
  cout<<fixed<<sqrt(pow(x1-x2,2)+pow(y1-y2,2))<<endl;
}
### Prompt

Please create a solution in cpp 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 <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
int main()
{
  double x1,y1,x2,y2;
  cin>>x1>>y1>>x2>>y2;
  cout<<fixed<<sqrt(pow(x1-x2,2)+pow(y1-y2,2))<<endl;
}
```