#include <iostream>
#include <cmath>
#include <stdio.h>

using namespace std;

int main(){
	double a,b,c,d;
	cin>>a>>b>>c>>d;

	double ans=sqrt(abs(c-a)*abs(c-a)+abs(d-b)*abs(d-b));
	printf("%.7f\n",ans);
	return 0;
}
### Prompt

Your challenge is to write 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 <iostream>
#include <cmath>
#include <stdio.h>

using namespace std;

int main(){
	double a,b,c,d;
	cin>>a>>b>>c>>d;

	double ans=sqrt(abs(c-a)*abs(c-a)+abs(d-b)*abs(d-b));
	printf("%.7f\n",ans);
	return 0;
}
```