Determine the number of elements a∈Zp2a \in \mathbb{Z}_{p^2}a∈Zp2 such that ap≡0(modp2)a^p \equiv 0 \pmod{p^2}ap≡0(modp2) for a prime ppp.
ppp
p−1p-1p−1
p+1p+1p+1
111