Please help me in prooving why this schme is not CCA secure, with a detailed example and distinguisher attack. I will rate, thank you!

1. Adding a plain hash to a plaintext does not result in CCA security. Consider the following approach for encryption, that uses a plain (unsalted) hash function H. To encrypt plaintext m, simply encrypt mH(m) under CTR mode. To decrypt, use normal CTR mode decryption but return err if the plaintext does not have the form mH(m) (i.e., if the last n bits are not a hash of the rest of the CTR-plaintext). Show that the scheme does not have CCA security