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

int main()
{
    double x1,x2,y1,y2,s;
    cin >> x1 >> y1 >> x2 >> y2;
    s = sqrt( pow(x1 - x2, 2) + pow(y1 - y2, 2));
    printf("%9.7f",s);
}

### Prompt

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

int main()
{
    double x1,x2,y1,y2,s;
    cin >> x1 >> y1 >> x2 >> y2;
    s = sqrt( pow(x1 - x2, 2) + pow(y1 - y2, 2));
    printf("%9.7f",s);
}

```