Conjugate prior, posterior distribution, mean and variance

For a multinomial distribution, find the conjugate prior, corresponding posterior and posterior mean/variance.

a a) Find the conjugate prior for a Multinomial distribution with parameter 0. Note that if x ~ Multinomial (O) then p(x|0) = 011022 ...OKK x0 where 01, ..., OK and 21, ..., XK are the components of the vectors 0 and x respectively. b) What is the corresponding posterior distribution? c) What are the posterior mean and variance