#include <iostream>
#include <cmath>
#include <stdio.h>
using namespace std;

int main(){
	double x1,y1,x2,y2,x,y,d;

	cin>>x1>>y1>>x2>>y2;
	x=abs(x1-x2);y=abs(y1-y2);

	d=sqrt(x*x+y*y);
	printf("%.10f\n",d);
	

}
### Prompt

Develop a solution in Cpp 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 <iostream>
#include <cmath>
#include <stdio.h>
using namespace std;

int main(){
	double x1,y1,x2,y2,x,y,d;

	cin>>x1>>y1>>x2>>y2;
	x=abs(x1-x2);y=abs(y1-y2);

	d=sqrt(x*x+y*y);
	printf("%.10f\n",d);
	

}
```