(In reply to Getting smarter?
by Steve Herman)
Actually it should be D1,
Even being ignorant of the pigeon principle, one must perceive that the answer is a function of the number quoted.
Replace it by a small figure, say 4 and count: 0,1,2,3 ...4 is banned, so only 4 could be the answer.
Ergo, the largest possible number of inhabitants is 483,207 (the non-existing quantity, like 4).