#include <iostream>
#include <cmath>
#include <cstdlib>

int main() {
    double x1{}, y1{}, x2{}, y2{};
    std::cin >> x1 >> y1 >> x2 >> y2;
    printf("%.8lf\n", pow(pow(x1-x2, 2.0) + pow(y1-y2, 2.0), 0.5));
}


### Prompt

In CPP, your task is to solve 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>
#include <cstdlib>

int main() {
    double x1{}, y1{}, x2{}, y2{};
    std::cin >> x1 >> y1 >> x2 >> y2;
    printf("%.8lf\n", pow(pow(x1-x2, 2.0) + pow(y1-y2, 2.0), 0.5));
}


```