#include <bits/stdc++.h>

using namespace std;

int main()
{
    double s;
    double sum;

    cin>>s;

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

    return 0;
}