#include<iostream> using namespace std; int main(){ int a; cin>>a; if(a <=2){ cout<<6<<endl; } if(a>2 && a <=10){ cout<<6+(a-2)*1.8<<endl; } if(a>10){ cout<< 6+(10-2)*1.8 + (a-10)*1.5*1.8<<endl; } return 0; }