#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=0,c=0,d=0; cin>>a; if(a<=2) cout<<6; else if(a<=10) cout<<6+(a-2)*1.8; else cout<<6+(10-2)*1.8+(a-10)*2.7; return 0; }