I have an idea, but I don't know how to solve it, so I need your help. Please tell me if you have any ways to solve it. Thanks.

Here is the problem:

Give you a tree with $$$ n $$$ nodes that have root, and there are $$$ a_i $$$ stones on the $$$ i $$$ node. Two players take turns operating. Any time, the player can move at least $$$ 1 $$$ stone (at most all stones) on one node to a son of it. The player who can't move will lost. Please calculate whether the first player will win or lost.

I don't know how to solve it, so I can't tell you the size of $$$ n $$$.