#include <bits/stdc++.h>
using namespace std;
int main()
{
  double x1,x2,y1,y2;cin>>x1>>y1>>x2>>y2;
  double X=pow(x2-x1,2);
  double Y=pow(y2-y1,2);
  cout<<fixed<<setprecision(12);
  cout<<sqrt(X+Y)<<endl;
}

### Prompt

Please formulate 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,x2,y1,y2;cin>>x1>>y1>>x2>>y2;
  double X=pow(x2-x1,2);
  double Y=pow(y2-y1,2);
  cout<<fixed<<setprecision(12);
  cout<<sqrt(X+Y)<<endl;
}

```