#include <iostream>

using namespace std;

int main()
{
    double a;
    double sum;

    cin>>a;

    if(a>=0 && a<=2000.00)  
        {
            cout<<"Isento"<<endl;
            return 0;
        }
    else if(a>=2000.01 && a<=3000.00)
                sum=(a-2000.01)*0.08;
    else if(a>=3000.01 && a<=4500.00)
                sum=(a-3000.01)*0.18+80;
    else if(a>4500.00)
                sum=(a-4500.00)*0.28+80+270;
    printf("R$ %.2lf",sum);

    return 0;
}