In this image, a drink is being poured into a system of pipes, with four glasses (labeled 1, 2, 3, and 4) waiting to be filled. Due to the structure of the pipes and blockages, only one glass will receive the wine first.

Upon inspecting the paths:

• Glass 1 is blocked.
• Glass 2 is blocked.
• Glass 4 is blocked.
• The only path open leads to Glass 3.

Therefore, Glass 3 will fill up first.