#include <iostream> //designed by lu 202509-0930 using namespace std; int main(){ int dis; float res=0.0; cin>>dis; if(dis<=2) { res = 6; } else if(dis<=10) { res = 6 + 1.8*(dis-2); } else { res = 6 + 1.8*(10-2)+(dis-10)*1.8*1.5; } cout<< res; return 0; }