#include<iostream> using namespace std; int main(){ double a,q; cin>>a; if(a<=2){ q=6; } if(a>2 && a<=10){ q=6+(a-2)*1.8; } if(a>10){ q=6+8*1.8+(1.8*0.5+1.8)*(a-10); } cout<<q; return 0; }