#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 a; cin>>a; double q=6; if(a<=2){ cout<<q<<endl; } else{ if(a<=10){ double qq=a-2; q=6+1.8*qq; cout<<q<<endl; } else{ double qqq=a-10; double qq=8; double qqqq=6+1.8*qq; q=qqqq+1.8*1.5*qqq; cout<<q<<endl; } } return 0; }