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