###Good writeup is at https://github.com/p4-team/ctf/tree/master/2015-12-05-seccon/paillier_crypto_200#eng-version
I use the fact that h=co (mod n*n) to brute force n, which took around 45 minutes.
Then I factor n to get p and q, and make into phi.
Then I plug everything into the "simpler variant" on https://en.wikipedia.org/wiki/Paillier_cryptosystem