#include<iostream> #include<cstdio> //scanf()\printf() #include<cstring> #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int km,y,n; cin>>km; if(km<=2){ cout<<6; } else if(km>2 && km<=10){ cout<<6+(km-2)*1.8; } else{ cout<<(6+(10-2)*1.8)+(km-10)*(1.8*1.5); } return 0; }