If I have a 1/171 chance of getting a certain item, and I need to collect all 171 items, what is the average number of attempts it will take?

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I am playing a game in which I need to earn 171 unique items to earn a trophy. There is a guaranteed drop of one item after every match, and I can get duplicates. Each item has an equal chance of dropping after every match, implying a 1/171 drop rate for each item. How many matches will I have to play, on average, before I collect each unique item given that I earn one every match?