Average number of feet anyone?

Save for those who have had an accident and have been unfortunate enough to have had a leg or foot amputated; the rest of us, I was under the impression (until recently) had two feet.

One would therefore assume that a simple purchase of shoes would require the same number of shoes as feet: Two.
Not so. Apparently some people may have more or less than two feet.  I wonder if they were concerned by the contents of their shoe box when opening it.

Will there be enough shoes for all my feet?  Or will I have spare shoes??
How did I come about this fascinating information?

The box from a recent purchase of trainers!!