#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(){ double a,b; cin>>a; if(a<=2){ b=6; } else if(10>=a>2){ b=6+1.8*(a-2); } else{ b=6+(1.8*8)+(1.8*1.5*(a-10)); } cout<<b; return 0; }