#include<iostream> #include<cstdio> using namespace std; int main(){ int m; double s; cin>>m; s=0; if(m>10){ s=6+(10-2)*1.8+(m-10)*1.8*1.5; }else{ if(m>2){ s=6+(10-2)*1.8; } else{ s=6; } } cout<<s<<endl; }