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

int main()
{
	double  x1,y1,x2,y2;
	cin >> x1>>y1>>x2>>y2;
	printf("%.9lf", sqrt(pow(x2 - x1, 2) + pow(y2 - y1, 2)));

	return 0;
}
### Prompt

Please create a solution in Cpp 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<stdio.h>
#include<math.h>
using namespace std;

int main()
{
	double  x1,y1,x2,y2;
	cin >> x1>>y1>>x2>>y2;
	printf("%.9lf", sqrt(pow(x2 - x1, 2) + pow(y2 - y1, 2)));

	return 0;
}
```