Quotients, Not Remainders.

• $X$ and $Y$ are positive integers.
• $X$ divided by $(Y - 1)$ gives a quotient of 4.
• $X$ divided by $(Y - 2)$ gives a quotient of 5.
• $X$ divided by $(Y - 3)$ gives a quotient of 6.

Let the number of the possible values of $X$ be $m$ . Let the number of possible values of $Y$ be $n$ .

Find $m$ + $n$ .