Any even number raised to any power will remain even. (e.g. 2² = 4, 2³ = 8, etc)
Any odd number raised to any power will remain odd. (e.g. 1² = 1³ = ... = 1, 3⁴ = 81, etc)
So
will always be even, since both
[even] - [odd] = [odd]
and
[odd] - [even] = [odd]