You and your friend decide to play the following game: You start with two piles of stones. The first with $n_1$ stones and the second with $n_2$ stones. You take turns, with your friend starting first. At each turn, a player can choose one of the two piles of stones, and pick any positive number of stones from this pile, and then you do the same. The person who picks the last stone wins. Suppose your friend start the game with an equal number of stones in each pile, show that you have a winning strategy.
Can anyone please help me with this problem .I am able to prove it with $n=1,2$ or $3$ where $n$ is the number of stones picked.But i m confused that how to proceed with a generalized proof