#include <iostream>
#include <cmath>
using namespace std;

int main()
{
	double x1, y1, x2, y2;
	cin >> x1 >> y1 >> x2 >> y2;
	cout << fixed << sqrt(pow(x2-x1, 2)+pow(y2-y1, 2));
	return 0;
}
### Prompt

Create a solution in CPP for 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>
using namespace std;

int main()
{
	double x1, y1, x2, y2;
	cin >> x1 >> y1 >> x2 >> y2;
	cout << fixed << sqrt(pow(x2-x1, 2)+pow(y2-y1, 2));
	return 0;
}
```