#include <bits/stdc++.h>
using namespace std;

int main(){
	double a,b,c,d,e,f,g,h=0;
	cin>>a>>b>>c>>d;
	e=c-a;
	f=d-b;
	g=e*e+f*f;
	h=sqrt(g);
	cout <<setprecision(12)<<h <<endl;
	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 <bits/stdc++.h>
using namespace std;

int main(){
	double a,b,c,d,e,f,g,h=0;
	cin>>a>>b>>c>>d;
	e=c-a;
	f=d-b;
	g=e*e+f*f;
	h=sqrt(g);
	cout <<setprecision(12)<<h <<endl;
	return 0;
}
```