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