Given that the gacha event has a geometric distribution for the number of failures X before winning, consider a card pool with a winning probability p of 0.005 for each card.

Each draw costs 50 units of currency. Today, five new characters with a winning probability of 0.005 each are added to the card pool. After failing Y times, the next draw will directly select one card from the new characters. From the perspective of the game developer, the minimum expected return for players aiming for a specific character is denoted as E[W]. Please write a Python program that, given the expected return specified by the developer, generates the corresponding guaranteed number of failures Y."