#include <iostream>
#include <cmath>
using namespace std;
int main()
{
	double x1, x2, y1, y2;
	cin >> x1 >> y1 >> x2 >> y2;
	printf("%.10lf\n", sqrt(abs(x1-x2)*abs(x1-x2) + abs(y1-y2)*abs(y1-y2))); 
}


### Prompt

Your task is to create 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>
using namespace std;
int main()
{
	double x1, x2, y1, y2;
	cin >> x1 >> y1 >> x2 >> y2;
	printf("%.10lf\n", sqrt(abs(x1-x2)*abs(x1-x2) + abs(y1-y2)*abs(y1-y2))); 
}


```