Schedule Handling

Harry is a busy person the fact that in his world, each week has $10$ days does not help him much. He has been assigned work for $N$ consecutive weeks. He created set $S$ of $schedules$ for the $N$ weeks. A $schedule$ is a set of days on which he has to work for each week. Formally, $schedule \subseteq \{1, 2, 3, 4, 5, 6, 7, 8, 9, 10\}$. Help harry find a non empty schedule $K$ such th