1.
Let $A$ be a set of $n$ integers.  Show there exists two subsets
$B,C$ such that $B$ is a proper subset of $C$ and
the sum of the elements in $B$ is congruent (mod $n$) to the
sum of the elements in $C$.



2. 
a)Let $S$ be the finite subsets of $\naturals$.
Show that $S$ is countable.

b)Show the set of functions $f:\naturals \to \naturals$ is uncountable.

