Mo. Rev. Stat. § 572.020: Gambling — penalty.

1. A person commits the offense of gambling if he or she knowingly engages in gambling.

2. The offense of gambling is a class C misdemeanor unless:

(1) It is committed by a professional player, in which case it is a class A misdemeanor; or

(2) The person knowingly engages in gambling with a child less than seventeen years of age, in which case it is a class B misdemeanor.