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

int main()
{
    double x1,x2,y1,y2,ans;
    cin>>x1>>y1>>x2>>y2;
    ans = (x2-x1)*(x2-x1) + (y2-y1)*(y2-y1);

    printf("%f\n", sqrt(ans));
}


### Prompt

Your task is to create 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,ans;
    cin>>x1>>y1>>x2>>y2;
    ans = (x2-x1)*(x2-x1) + (y2-y1)*(y2-y1);

    printf("%f\n", sqrt(ans));
}


```