#include <stdio.h>
#include <math.h>
int main() {
  double x1,y1,x2,y2,x;
  scanf("%lf %lf %lf %lf", &x1, &y1, &x2, &y2);
  x = sqrt(pow(x2-x1,2.0) + pow(y2-y1,2.0));
  printf("%lf\n", x);
  return 0;
}


### Prompt

In CPP, your task is to solve 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,x;
  scanf("%lf %lf %lf %lf", &x1, &y1, &x2, &y2);
  x = sqrt(pow(x2-x1,2.0) + pow(y2-y1,2.0));
  printf("%lf\n", x);
  return 0;
}


```