have := Iff.mp Nat.odd_iff_not_even this
case h
n : Nat
h : n > 0
a✝ : Even n
h' : ¬Odd (n - 1)
this✝ : Even (n - 1)
this : Odd n
⊢ False
case h
n : Nat
h : n > 0
a✝ : Even n
h' : ¬Odd (n - 1)
this✝¹ : Even (n - 1)
this✝ : Odd n
this : ¬Even n
⊢ False