#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){ cout<<6; } else if (a>2 && a<=10){ b=6+(a-2)*1.8; cout<<b; } else { b=6+(10-2)*1.8+(a-10)*(1.8+0.9); cout<<b; } return 0; }