# Lottery also comes in numbers!

**Discrete Mathematics**Level 5

Let us call a lottery **lucky** if the sum of the first 3 digits are equal to the last 3 digits. For example, \(456177\) is lucky because \(4+5+6 = 1+7+7\).

And let us call a lottery **good** if the sum of all digits is 27. For example, \(345456\) is good because \(3+4+5+4+5+6 = 27\).

If the number of different possible lotteries that are **lucky** is \(a\), and the number of different possible lotteries that are **good** is \(b\), find the value of \(a-b\).

This question is from Thailand Math POSN, Combinatorics.