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


int main()
{
	double a, b, c, d, e;
	cin >> a >> b >> c >> d;
	e = sqrt(pow(c-a, 2) + pow(d-b, 2));
	printf("%0.6f\n", e);
	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<cstdio>
#include<cmath>
using namespace std;


int main()
{
	double a, b, c, d, e;
	cin >> a >> b >> c >> d;
	e = sqrt(pow(c-a, 2) + pow(d-b, 2));
	printf("%0.6f\n", e);
	return 0;
}


```