#include <bits/stdc++.h>
using namespace std;

int main(void){
	double x1, x2, y1, y2;

	cin >> x1 >> y1 >> x2 >> y2;
	printf("%.8f\n", sqrt((x1 - x2)*(x1 - x2) + (y1-y2)*(y1-y2)));

	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 <bits/stdc++.h>
using namespace std;

int main(void){
	double x1, x2, y1, y2;

	cin >> x1 >> y1 >> x2 >> y2;
	printf("%.8f\n", sqrt((x1 - x2)*(x1 - x2) + (y1-y2)*(y1-y2)));

	return 0;
}
```