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