Alice and Bob are playing a game. It is played in 1*N grids. Each grid can be occupied by one stone. Alice has K white stones on the left (numbered 1 to K from left to right), and Bob has K black stones on the right (numbered 1 to K from right to left). They take turns to move their own stones, and Alice moves first. In each move, the player must choose one stone to move to the nearest empty grid forward (Alice moves to the right, Bob moves to the left). If one player cannot find any stone to move, he wins.
Now Alice asks you to find a winning strategy of the game. Can you help him?