**First Hint:** Start by analyzing the frequency of each character in the `target` string and in each sticker. Determine which stickers can contribute the most to covering the characters in `target`.

**Second Hint:** Use a dynamic programming (DP) approach where `dp[mask]` represents the minimum number of stickers needed to form the characters represented by the bitmask `mask`. The bitmask should encode the frequency of characters in `target` (e.g., if `target` has 2 't's, the bitmask should account for this).

**Third Hint:** For each state in the DP (represented by a bitmask), iterate through all stickers and update the DP state by applying the sticker's character frequencies to the current state. The goal is to reduce the remaining characters needed (i.e., reduce the bitmask) with each sticker application.