Could you please explain the problem statement more. I can think ofthreeinterpretations

1) We pick 8 shoes

2) We pick 16 shoes, in pairs

3) We pick 16 shoes, one by one

The difference between (2) and (3) is:

if we select 12 12 34 34 56 56 78 78

then for (2) we do not have a complete pair; for (3) we have 8 complete pairs.