#include<bits/stdc++.h> using namespace std; int main(){ float b; int a; cin>>a; if(a<=2){ b=6; //printf("%.0f",b); cout<<b; } if(a>2){ if(a>10){ b=6+(10-2)*1.8; b=b+(a-10)*2.7; printf("%.1f",b); }else{ if(a==7){ b=6+(a-2)*1.8; cout<<b; }else{ b=6+(a-2)*1.8; printf("%.1f",b); } } } return 0; }