# include<stdio.h> # include<iostream> # include<cstdio> using namespace std; int main(){ int s; double fee; cin>>s; if(s<=2) fee=6.0; else if(s<=10) fee=6+1.8*(s-2); else fee=6+1.8*8+1.8*1.5*(s-10); printf("%lf",fee); return 0; }