#include<cstdio>
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;
}