Exponentiation mistake

Algebra Level 3

Murray doesn't really understand how to exponentiate negative numbers. He thinks that negative numbers are aliens from another planet that he can't be bothered with, so he writes

$(-a)^b = a^b.$

How many of the $10 \times 10$ ordered pairs of integers $(a, b)$ , each of which are between 1 and 10 inclusive, satisfy

$(-a)^b = a^b ?$