#include<iostream>
#include<cstdio>
#include<math.h>
using namespace std;
int main(){
	double x1,y1,x2,y2,a,b,c,ans;
	cin>>x1>>y1>>x2>>y2;
	a=x1-x2;
	b=y1-y2;
	ans=sqrt(a*a+b*b);
	printf("%.8f",ans);
	
}
### 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<cstdio>
#include<math.h>
using namespace std;
int main(){
	double x1,y1,x2,y2,a,b,c,ans;
	cin>>x1>>y1>>x2>>y2;
	a=x1-x2;
	b=y1-y2;
	ans=sqrt(a*a+b*b);
	printf("%.8f",ans);
	
}
```