Johnny, the White monarch, is homesick, and his friend Carla, the h1 rook, is away, using her time to help the lower citizens of the Black kingdom. They use to do such wonderful fun, but their favorite act was a form of dance known as castling. Recently, he gave Carla a call, and she agreed to come back for another such ance, but this time in reverse. But Carla wishes to know the quickest way to reach the dance floor to save on travel expenses.
Help Johnny and Carla plan their journey with efficiency; What is the minimum amount of plies, the currency of both kingdoms, needed to reach the dance floor and "untango," aka uncastle, in the current state of the traffic system, i.e. the board? The Black kingdom is willing to help them out, but they must do so legally, traveling with their documentation, and must not leave behind anything illegal behind.
Andriy Frolkin, Die Schwalbe 12/1986