quickly playing with numbers gets me to say 11 and that is probably the best way to solve this.

We know that n-2 is divisible by 3 and n-1 is divisible by 5. So just look at numbers that end in 6 and 1 (n-1 is divisible by 5) and find one where n-2 is also divisible by 3. The first one you get is 11.