If n leaves a remainder of 1 divided by 4:

then if the first player pick k stones, the second player can 4-k to make the number of rest stone always leaves a remainder of 1 divided by 4. the second player always win the game.

In other case,

if n leaves a remainder of r (r=2,or 3) divided by 4:

the first player pick r-1 stones at the first step. and then If the second pick i stones, he will pick 4-i stone to make the number of rest stones always leaves a remainder of 1. the first player win the game!

if n leaves a remainder of 0 divided by 4, then the first player will pick 3 stones, after that he adopt the similar strategy mentioned above, he always win the game!