#include<cstdio>
#include<cmath>
int main(){
        double x1,y1,x2,y2;
        scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);
        printf("%.10lf\n",sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)));
        return 0;
}
### Prompt

Please create a solution in Cpp 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<cstdio>
#include<cmath>
int main(){
        double x1,y1,x2,y2;
        scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);
        printf("%.10lf\n",sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)));
        return 0;
}
```