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

int main()
{

    double x1,y1,x2,y2;
    cin>>x1>>y1>>x2>>y2;

    cout << fixed << setprecision(15) << sqrt(pow(x2-x1,2)+pow(y2-y1,2)) << 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()
{

    double x1,y1,x2,y2;
    cin>>x1>>y1>>x2>>y2;

    cout << fixed << setprecision(15) << sqrt(pow(x2-x1,2)+pow(y2-y1,2)) << endl;

    return 0;
}  

```