106. Imperial Waltz
Amy grabs onto the ghostly dancer and, using him to steady herself, is able to regain her feet. The dancer looks surprised and a bit confused at Amy's attire, but is overall happy to have a partner. Amy smiles sweetly at him, and the pair proceeds to the floor just as the music stops. A loud voice with a slight German accent booms, seemingly from nowhere.
“Alright, ladies und gentlemen, up next we have the Daventry Waltz. Grab your partners! And a-one, and a-two, and a-three!”
Amy panics. She's trying to remember her dance classes. She thinks she can recall a few basic steps, enough to get by, but some are for a song of three beats per measure, another for four beats. Which is a waltz?
Help Amy out! How many beats to a measure is a waltz?