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