#include <iostream>
using namespace std;
int main()
{
double x;
scanf ("%lf", &x);
double sum=0;
if (x>2000)
{
double y=3000;
if(x<3000)y=x;
sum +=(y-2000)*0.08;
}
if(x>3000)
{
double y=4500;
if(x<4500)y=x;
sum+=(y-3000)*0.18;
}
if(x>4500) sum +=(x-4500)*0.28;
if(sum==0)printf("Isento");
else printf("R$ %.2lf\n",sum);
return 0;
}