How many boots must you take in order to be sure you get a pair of boots that match?

This answer varies depending on how many boots exist. If there are 1000 boots, then 1001 are needed to make sure that a pair of boots matches. If there are 100 boots, then 101 are needed etc.
3

Actually, it would be 13 since you may take out 12 shoes for the left/right foot. Therefore, you need to take out one more!