#include
using namespace std;
int main()
{
double x,y;
cin>>x;
if(0<x<=240)
{y=0.4883x;
printf("%.2lf",y);
}
else if(240<x<=400)
{y=0.4883*240+(x-240)*0.5383;
printf("%.2lf",y);
}
else if(x>400)
{y=2400.4883+160*0.5383+(x-400)*0.7883;
printf("%.2lf",y);
}
return 0;
}