#include <iostream>
#include <cstdio>

using namespace std;

int main()
{
    double x, ans;
    cin >> ans;

    if (x <= 2000) cout << "Isento";
    else
    {
        if (x > 4500) ans += (x - 4500) * 0.28, x = 4500;
        if(x > 3000) ans += (x - 3000) * 0.18, x = 3000;
        if(x > 2000) ans += (x - 2000) * 0.08;

        printf("R$ %.2f", ans);
    }



    return 0;
}