Determine the topic of the question. Question: "what are four thirds cameras?" Topic:
Ans: Four Thirds system

Determine the topic of the question. Question: "when was the first nfl madden game released?" Topic:
Ans: Madden NFL

Determine the topic of the question. Question: "how many users do twitter have?" Topic:
Ans: Twitter

Determine the topic of the question. Question: "what is a .PAC file?" Topic:
Ans: Proxy auto-config