#include <bits/stdc++.h>

using namespace std;

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

  scanf("%lf %lf %lf %lf", &x1, &y1, &x2, &y2);

  ans = pow(x2 - x1, 2) + pow(y2 - y1, 2);

  printf("%lf", sqrt(ans));
}

### Prompt

Create a solution in cpp for 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 x1, y1, x2, y2, ans;

  scanf("%lf %lf %lf %lf", &x1, &y1, &x2, &y2);

  ans = pow(x2 - x1, 2) + pow(y2 - y1, 2);

  printf("%lf", sqrt(ans));
}

```