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

int main(){
  double x1,y1,x2,y2;

  scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);

  printf("%f\n",sqrt((pow(x2-x1,2.0)+pow(y2-y1,2.0))));


  return 0;
}


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

int main(){
  double x1,y1,x2,y2;

  scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);

  printf("%f\n",sqrt((pow(x2-x1,2.0)+pow(y2-y1,2.0))));


  return 0;
}


```