Number Game Revisited

Alice and Bob play the following game.They choose a number N to play with.The runs are as follows : 1.Bob plays first and the two players alternate. 2.In his/her turn ,a player can subtract from N any prime number(including 1) less than N.The number thus obtained is the new N. 3.The person who cannot make a move in his/her turn loses the game. Assuming both play optimally,who wins the game ?