#include <iostream>

using namespace std;

int main(void)
{
    double wage;
    double total = 0;

    cin >> wage;

    if (wage <= 2000) {
        cout << "Isento" << endl;
    } else if (wage >= 2000.01 && wage <= 3000) {
        total = (wage - 2000) * 0.08;
        printf("R$ %.2f\n", total);
    } else if (wage >= 3000.01 && wage <= 4500) {
        double tax1 = 1000 * 0.08;
        double tax2 = (wage - 3000) * 0.18;
        total = tax1 + tax2;
        printf("R$ %.2f\n", total);
    } else if (wage > 4500) {
        double tax1 = 1000 * 0.08;
//      printf("tax1 %.2f\n", tax1);
        double tax2 = 1500 * 0.18;
//      printf("tax2 %.2f\n", tax2);
        double tax3 = (wage - 4500) * 0.28;
//      printf("tax3 %.2f\n", tax3);
        total = tax1 + tax2 + tax3;
        printf("R$ %.2f\n", total);
    }

    return 0;
}