#include<iostream>
#include<cmath>
#include<cstdio>
using namespace std;
int main()
{
	double x1,x2,y1,y2,x,y,z;
	cin>>x1>>y1>>x2>>y2;
	x=x2-x1;
	y=y2-y1;
	x *=x;
	y *=y;
	z=sqrt(x+y);
	printf("%lf\n",z);
	return 0;
}
### Prompt

Please formulate 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<cstdio>
using namespace std;
int main()
{
	double x1,x2,y1,y2,x,y,z;
	cin>>x1>>y1>>x2>>y2;
	x=x2-x1;
	y=y2-y1;
	x *=x;
	y *=y;
	z=sqrt(x+y);
	printf("%lf\n",z);
	return 0;
}
```