#include<iostream> using namespace std; int main(){ double sum2; int a; cin>>a; if(a<=2){ sum2=6; }else if(a>2 && a<=10){ sum2=6+(a-2)*1.8; }else if(a>10){ sum2=6+(10-2)*1.8+(a-10)*1.8*1.5; } printf("%.1lf",sum2); return 0; }