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

int main(void) {
  double a, b, c, d;
  scanf("%lf%lf%lf%lf", &a, &b, &c, &d);
  printf("%f\n", sqrt((a - c) * (a - c) + (b - d) * (b - d)));
  return 0;
}

### Prompt

Please provide a CPP coded solution to the problem described below:

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(void) {
  double a, b, c, d;
  scanf("%lf%lf%lf%lf", &a, &b, &c, &d);
  printf("%f\n", sqrt((a - c) * (a - c) + (b - d) * (b - d)));
  return 0;
}

```