#include <iostream>
#include <cstdio>
using namespace std;
int main(){
    double wages;    cin >> wages;
    double tag = 0;
    if(wages <= 2000.0) cout << "Isento" << endl;
    else if(wages <= 3000.0)    printf("R$ %.2lf\n", (wages - 2000) * 0.08);
    else if(wages <= 4500){
        tag += 1000 * 0.08;
        printf("R$ %.2lf\n", (wages - 3000) * 0.18 + tag);
    }else{
        tag += 1500 * 0.18 + 1000 * 0.08;;
        tag += ((wages - 4500.0) * 0.28);
        printf("R$ %.2lf\n", tag);
    }
    return 0;
}