Let $f_m(n)$ count the number of maximal sum-free subsets $A\subseteq \{1,\dots ,n\}$ - that is, there are no solutions to $a=b+c$ in $A$ and $A$ is maximal with this property. Estimate $f(n)$ - is it true that $f_m(n)=o(2^{n/2})$?