#include<iostream>
#include<cmath>
using namespace std;
int main(){
	double a,b,c,d,x,y;
	cin>>a>>b>>c>>d;
	x=a-c;
	x*=x;
	y=b-d;
	y*=y;
	double z = sqrt(x+y);
	cout<<fixed<<z<<endl;
	return 0;
}
### Prompt

Please provide a Cpp coded solution 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>
using namespace std;
int main(){
	double a,b,c,d,x,y;
	cin>>a>>b>>c>>d;
	x=a-c;
	x*=x;
	y=b-d;
	y*=y;
	double z = sqrt(x+y);
	cout<<fixed<<z<<endl;
	return 0;
}
```