long long int n;
        cin>>n;
        long long int curr=0,prev=0,ans=0,next;
        curr=2;
        prev=0;
        ans=2;
        for(int i=1;i<=n;i++)
        {
            next=4*curr + prev;
            if(next>n)
            {
                cout<<ans<<endl;
                break;
            }
            ans=ans+next;
            prev=curr;
            curr=next;
            
        }