Prove that only one of the numbers m-1, m+1and m+3 is divisible by 3 where m is any positive integer

Prove that only one of the numbers m-1, m+1and m+3 is divisible by 3 w

1.	Prove that only one of the numbers m-1, m+1and m+3 is divisible by 3 where m is any positive integer
Answer» ?so easy