#include<bits/stdc++.h> using namespace std; int main(){ float b; int a; cin>>a; if(a<=2){ b=6; printf("%.0f",b); }if(a>2){ b=6+(a-2)*1.8; if(a>10){ b=b+(a-10)*2.7; printf("%.1f",b); }else{ printf("%.1f",b); } } return 0; }