#include <iostream>
#include <cmath>
#include <cstdio>
using namespace std;
int main(){
	double x1,y1,x2,y2;
	cin>>x1>>y1>>x2>>y2;
	double a=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
	printf("%lf\n",a);

}
### Prompt

Construct a CPP code solution to the problem outlined:

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 <iostream>
#include <cmath>
#include <cstdio>
using namespace std;
int main(){
	double x1,y1,x2,y2;
	cin>>x1>>y1>>x2>>y2;
	double a=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
	printf("%lf\n",a);

}
```