intro d (_ : n + step d ≃ m)
ℕ : Type
inst✝³ : Core ℕ
inst✝² : Induction ℕ
inst✝¹ : Addition ℕ
inst✝ : Sign ℕ
order_inst : Order ℕ
n m : ℕ
x✝ : n ≤ m
d : ℕ
⊢ ∀ (m_1 : ℕ), n + step m_1 ≃ m → n < m ∨ n ≃ m
ℕ : Type
inst✝³ : Core ℕ
inst✝² : Induction ℕ
inst✝¹ : Addition ℕ
inst✝ : Sign ℕ
order_inst : Order ℕ
n m : ℕ
x✝¹ : n ≤ m
d✝ d : ℕ
x✝ : n + step d ≃ m
⊢ n < m ∨ n ≃ m