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

int main() {
    double x, y, m, n;
    cin >> x >> y >> m >> n;
    
    cout << fixed << setprecision(4) << hypot(x - m, y - n);
}

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

int main() {
    double x, y, m, n;
    cin >> x >> y >> m >> n;
    
    cout << fixed << setprecision(4) << hypot(x - m, y - n);
}

```