• Exactly n moves, or at most n moves?

Question related to mission Chess Knight

 

Let's say the knight is on a1, and number of moves is 2. It seems that the result includes b3, but it's impossible to get from a1 to b3 in exactly 2 moves. So, I suppose the intended semantics is "at most n moves".

But then, when n=1, why is a1 not in the set?? You can get from a1 to a1 in at most 1 step: namely, in 0 steps. Zero is a number. I really think the task is inconsistent, requiring the understanding of exactly one step when n=1, and at most two steps when n=2. :-/ Please fix.