#include<iostream>
#include<math.h>
#include<stdio.h>
using namespace std;

int main()
{
  double x,y,x1,y1;
  cin>>x>>y>>x1>>y1;
  printf("%.8f\n",sqrt((x1-x)*(x1-x)+(y1-y)*(y1-y)));
  return 0;
}
### Prompt

Please provide a cpp coded solution to the problem described below:

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<math.h>
#include<stdio.h>
using namespace std;

int main()
{
  double x,y,x1,y1;
  cin>>x>>y>>x1>>y1;
  printf("%.8f\n",sqrt((x1-x)*(x1-x)+(y1-y)*(y1-y)));
  return 0;
}
```