#include<iostream>
using namespace std;
int main(){
    double x,y;
    scanf("%lf",&x);
    if(x<=2000) cout<<"Isento";
        else if(x<=3000) printf("R$ %.2lf",(x-2000)*0.08);
        else if(x<=4500) printf("R$ %.2lf",(3000-2000)*0.08+(x-3000)*0.18);
        else if(x<=5000) printf("R$ %.2lf",(3000-2000)*0.08+(4500-3000)*0.18+(x-4500)*0.28);
}