include[HTML_REMOVED]

include[HTML_REMOVED]

include[HTML_REMOVED]

using namespace std;
int main()
{
double x1,x2,y1,y2,d;
scanf(“%lf%lf\n%lf%lf”,&x1,&y1,&x2,&y2);
d=sqrt((x2-x1)(x2-x1)+(y2-y1)(y2-y1));
printf(“%.4f”,d);
return 0;
}