To start the game, there are twenty-one (21) flags available. The object of the game is to be the person who takes the last flag. On your turn you may take one (1), two (2) or three (3) flags. Once you submit your choice, the computer will then take one (1), two (2) or three (3) flags. You will continue to take turns until someone has taken the last flag. If you want to win, do not make a mistake and let the computer gain the advantage.

There are 21 flags remaining. Take one (1), two (2) or three (3) flags.

How many flags?