#include <iostream> #include <cstdio> using namespace std; int main(){ int n; cin>>n; double s; if(n<=2){ s=6;} if(2<n<=10){ s=6+(n-2)*1.8;} if(n>10){ s=6+8*1.8+(n-10)*1.8*1.5; } cout<<s<<endl; }