Problem #1:

Suppose N objects are distributed between B boxes in such a way that no box is empty. How many objects must we choose in order to be sure that we have chosen the entire contents of at least one box?

My strategy was to find out the maximum number of contents one box can have, say M.

Then if I choose M objects I can satisfy the given task.

But I'm stuck on finding this maximum number.

I know that by using the pigeonhole principle, I can sayat least onebox has at most or at least some number of contents.

How can I sayallboxes have at most some number of contents?

Problem #2:

There are twelve signs of the Western Zodiac. Suppose there are 145 people in a room. Show that there must be 13 people who share the same sign of the Western Zodiac.

I'm confused about the wording. Is the problem different from "show that there must be at least 13 people who share a zodiac"?

If so, I need hints to find how to narrow down from saying "at least 13 people share one zodiac" to "exactly 13 people share one zodiac".