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

int main() {
double a,b,c,d;
cin>>a>>b>>c>>d;
printf("%.10f",sqrt(abs(a-c)*abs(a-c)+abs(b-d)*abs(b-d)));

}
### Prompt

Construct a cpp code solution to the problem outlined:

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 a,b,c,d;
cin>>a>>b>>c>>d;
printf("%.10f",sqrt(abs(a-c)*abs(a-c)+abs(b-d)*abs(b-d)));

}
```