#include <stdio.h>
#include <math.h>
int main(void) {

	double x1, y1, x2, y2;

	scanf("%lf %lf %lf %lf", &x1, &y1, &x2, &y2);
	printf("%10.8lf", sqrt((x2 - x1) * (x2 - x1 ) + ( y2 - y1) * ( y2 - y1 )));

}
### 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(void) {

	double x1, y1, x2, y2;

	scanf("%lf %lf %lf %lf", &x1, &y1, &x2, &y2);
	printf("%10.8lf", sqrt((x2 - x1) * (x2 - x1 ) + ( y2 - y1) * ( y2 - y1 )));

}
```