#include <cstdio>
#include <cmath>

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

    scanf("%lf %lf %lf %lf", &x1, &y1, &x2, &y2);
    
    printf("%lf\n", sqrt(pow((x2-x1),2)+pow((y2-y1),2)));

    return 0;
}
### 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 <cstdio>
#include <cmath>

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

    scanf("%lf %lf %lf %lf", &x1, &y1, &x2, &y2);
    
    printf("%lf\n", sqrt(pow((x2-x1),2)+pow((y2-y1),2)));

    return 0;
}
```