#include <iostream>
#include <cmath>

int main()
{
    double x1,y1,x2,y2;

    std::cin >> x1 >> y1 >> x2 >> y2;

    std::printf("%lf", sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)));

    return 0;


}
### 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 <iostream>
#include <cmath>

int main()
{
    double x1,y1,x2,y2;

    std::cin >> x1 >> y1 >> x2 >> y2;

    std::printf("%lf", sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)));

    return 0;


}
```