Given an elliptic curve over $\mathbb Z_n$ 1. Is it $\#P$ hard to compute $\# E(\mathbb Z_n)$? 2. Is it $PP$-hard to compute $\# E(\mathbb Z_n)\leq\frac n2$? 3. Is it $\oplus P$ hard to compute $\# E(\mathbb Z_n)\bmod 2$?