It's dark. You have ten grey socks and ten blue socks you want to put into pairs. All socks are exactly the same except for their colour. How many socks would you need to take with you to ensure you had at least a pair?
the answer is 3 since the first one is one color, the second one will be the opposite color and the third one can be any color.
the second one MIGHT be the opposite color, so you need a third sock to be certain of a match
