#include <stdio.h>
#include <math.h>
int main(){
    double x,y,a,b;
    scanf("%lf%lf%lf%lf",&x,&y,&a,&b);
    printf("%lf\n",sqrt((x-a)*(x-a)+(y-b)*(y-b)));
}
### 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 <stdio.h>
#include <math.h>
int main(){
    double x,y,a,b;
    scanf("%lf%lf%lf%lf",&x,&y,&a,&b);
    printf("%lf\n",sqrt((x-a)*(x-a)+(y-b)*(y-b)));
}
```