#include <cstdio>
#include <cmath>

int main(){
	double x1, x2, y1, y2;
	
	scanf(" %lf %lf %lf %lf", &x1, &y1, &x2,&y2);
	printf("%lf\n", sqrt( pow(x2-x1, 2.0) + pow(y2- y1, 2.0) ));
	
	return 0;
}
### Prompt

Please formulate 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 <cstdio>
#include <cmath>

int main(){
	double x1, x2, y1, y2;
	
	scanf(" %lf %lf %lf %lf", &x1, &y1, &x2,&y2);
	printf("%lf\n", sqrt( pow(x2-x1, 2.0) + pow(y2- y1, 2.0) ));
	
	return 0;
}
```