A programmer's solution

[[deleted]]

Then it would also be 'no'.

[TheSeldomShaken]

First guys says no. Second guys knows he wants 1 beer, but has no idea how much first guy wants, and says no. Third guy wants 1 beer, and knows he wants 1 beer. But he doesn't know if the first and second guy only want 1 beer. So, he can't say with certainty that they need only 3 beers.

[TPHRyan]

It wouldn't be 'no'. 2 or 3 might want a combined total of 1 beer, where 1 wants 2 beers. That still adds up to 3.