#include <stdio.h>
#include <cmath>


int main() {
  double x1,y1,x2,y2;
  scanf("%lf %lf %lf %lf",&x1,&y1,&x2,&y2);
  double d = sqrt(pow((x1-x2),2) + pow((y1 - y2),2));
  printf("%lf",d);
}

### 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 <stdio.h>
#include <cmath>


int main() {
  double x1,y1,x2,y2;
  scanf("%lf %lf %lf %lf",&x1,&y1,&x2,&y2);
  double d = sqrt(pow((x1-x2),2) + pow((y1 - y2),2));
  printf("%lf",d);
}

```