Problem help

I came across this Atcoder problem Problem G but I couldn’t understand even a bit of the editorial. Can anyone explain it in a more beginner friendly manner? Thank you!

Well first it’s asking for the expected value (probability) which is explained here: The game you are sampling a card and putting it back so out of 2 cards with 1 and 2 written on them could draw the 1 or 2 multiple times. Expected value means you are playing many iterations of this game and on average what is the amount of times you play to find all the integers.

First example you have 2 cards, with each card having an integer written on it from 1 to 2. There is one card with from 1 to 1 written on it (or 1) and one card with M written on it (2). Now the expected value is what if you draw 2 cards (1/2 probability) and find all the integers plus what if you draw 3 cards to find all the numbers (1/4 probability) tl;dr given the constraints of 2 cards with 1 and 2 written on them what is the expected number of times of playing this game until you get all the integer values and their solution is 3.

I’m not really sure the second input with the C’s it seems like it could be the amount of cards from 1 to i with that integer or it could be something else you’d have to write out some examples to figure it out