#include<bits/stdc++.h> using namespace std; int main() { double b; cin>>b; if(b>10){ cout<<6+(b-10)*1.8+(b-10)*1.8*1.5<<endl; } else if(b<=10&&b>2){ cout<<(b-2)*1.8+6<<endl; } else{ cout<<6<<endl; } return 0; }