#include<iostream> #include<cstdio> #include<cstring> #include<cmath> using namespace std; int main(){ int a,b; cin>>a; if(a<2){ cout<<6<<endl; }else if(a<10){ cout<<(a-2)*1.8+6<<endl; }else if(a>10){ cout<<(a-10)*1.8*1.5+6+(a-2)*1.8<<endl; } return 0; }