#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;

int main() {
    double x1, y1, x2, y2;
    cin >> x1 >> y1 >> x2 >> y2;
    printf("%lf\n", sqrt(pow(x1 - x2, 2) + pow(y1 - y2, 2)));
}
### 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<cstdio>
#include<cmath>
using namespace std;

int main() {
    double x1, y1, x2, y2;
    cin >> x1 >> y1 >> x2 >> y2;
    printf("%lf\n", sqrt(pow(x1 - x2, 2) + pow(y1 - y2, 2)));
}
```