using namespace std;
long long t,x,n,s1,s2=1;
int main()
{
	cin>>n;
	t=n;
	while(n)
	{
		x=n%10;
		n=n/10;
		s1=s1+x;
		s2=s2*x;
	}
	if(t%2==0) cout<<s1;
		else cout<<s2;
}