Write a question about the following article: Interested in sports and athletically inclined from a young age, Thompson co-founded the Hawks Athletic Club while attending I.N. Bloom Elementary School, which led to an invitation to join Louisville's Castlewood Athletic Club, a club for adolescents that prepared them for high-school sports. Ultimately he never joined any sports teams in high school. Thompson attended I.N. Bloom Elementary School, Highland Middle School, and Atherton High School, before transferring to Louisville Male High School in September 1952. Also in 1952, he was accepted as a member of the Athenaeum Literary Association, a school-sponsored literary and social club that dated to 1862. Its members at the time, generally drawn from Louisville's wealthy upper-class families, included Porter Bibb, who later became the first publisher of Rolling Stone at Thompson's behest. During this time Thompson read and admired J. P. Donleavy's The Ginger Man. As an Athenaeum member, Thompson contributed articles to and helped produce the club's yearbook The Spectator. The group ejected Thompson in 1955, citing his legal problems. Charged as an accessory to robbery after being in a car with the perpetrator, Thompson was sentenced to 60 days in Kentucky's Jefferson County Jail. He served 31 days and, a week after his release, enlisted in the United States Air Force. While he was in jail, the school superintendent refused him permission to take his high-school final examinations, and as a result he did not graduate.

Question about the article:
How many days early did Thompson get out of jail?