Hello everyone, I'm trying to solve a applied stochastic process problem and even the example is beautiful, I don't know how to approach it. Here the problem:

10 men want to get out of a bar, they do it in the following way: Initially they store all 10 umbrella in a basket next to the exit from the pub. They go all together and each one picks an umbrella at random. Those who picked their own umbrellas leave while those who picked a wrong umbrella, put it back and return to a pub for another glass of beer. After that they return to the basket and try once again. And so on. Let T be the number of rounds needed for all men to leave, and let N be the total number of beers consumed during the procedure. a) Compute E(T) b) Compute E(N)

Can someone help me, also in how to put this problem in a appropriate model.

Thank you