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