intro a ha
case h.e'_2
x : ℤ
hx : ¬x = 0
⊢ ∀ (a : ℤ), a ∈ UniqueFactorizationMonoid.normalizedFactors x → 2 = a ∨ Odd a
case h.e'_2
x : ℤ
hx : ¬x = 0
a : ℤ
ha : a ∈ UniqueFactorizationMonoid.normalizedFactors x
⊢ 2 = a ∨ Odd a