Codechef Puzzle: NUMGAME

So I encounter this interesting problem NUMGAME at Codechef. This is in the list of easy problems.
At first I was lost after looking the problem and could not think of how to solve it but when I came to thinking about it, it seems that it is quite easy.

Hints: (Obvious but important)

1) An odd number is always formed by the multiplication of two odd numbers.
2) If you substract an odd number from an odd number then it gives you an even number.