Question 505168
You'll have to explain the problem, because very few of us will know that the Kaliningrad Circus problem is, and almost none will have your textbook. Google lists a "Kaliningrad problem" that pertains more to economics and has nothing to do with circuses. Also, Kaliningrad was formerly named Königsberg, and there is a famous problem in graph theory called the Königsberg bridge problem, in which you had to cross the bridges of Königsberg without going over the same bridge twice.