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

int main()
{
	double ax, ay, bx, by;
	cin >> ax >> ay >> bx >> by;
	printf("%.6f\n",sqrt(pow(bx-ax,2)+pow(by-ay,2)));
    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 ax, ay, bx, by;
	cin >> ax >> ay >> bx >> by;
	printf("%.6f\n",sqrt(pow(bx-ax,2)+pow(by-ay,2)));
    return 0;
}
```