#include <cstdio>
#include <iostream>
//#include <cmath>
using namespace std;

int main()
{
    double a,b=0;
    cin >> a;
    if(a<=2000)
        printf("Isento");
    else if(a<=3000)
    {
        b=a-2000;
        b*=0.08;
        printf("R$ %.2f",b);
    }
    else if(a<=4500)
    {
        b=1000*0.08+(a-3000)*0.18;
        printf("R$ %.2f",b);
    }
    else 
    {
        b=1000*0.08+1500*0.18+(a-4500)*0.28;
        printf("R$ %.2f",b);
    }
    return 0;
}