#include <stdio.h>
#include <math.h>

int main(){
  double x1, y1, x2, y2;
  scanf("%lf%lf%lf%lf", &x1, &y1, &x2, &y2);
  printf("%lf\n", pow(pow(x1 - x2, 2) + pow(y1 - y2, 2), 0.5));
}


### Prompt

Your challenge is to write 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 <stdio.h>
#include <math.h>

int main(){
  double x1, y1, x2, y2;
  scanf("%lf%lf%lf%lf", &x1, &y1, &x2, &y2);
  printf("%lf\n", pow(pow(x1 - x2, 2) + pow(y1 - y2, 2), 0.5));
}


```