I've implemented this problem two different ways and I have WA9 on both of them. I'm possibly interpreting the problem wrong, but I've read the problem over and over again and I cannot come up with an alternative interpretation. Can someone please shine some light?

Если у кого ещё такая проблема есть, то это,как вариант, связано с нечетным n  (последний человек ни разу не дежурит)