Theorem nnzi

Description: A positive integer is an integer. (Contributed by Mario Carneiro, 18-Feb-2014)

	Ref	Expression
Hypothesis	nnzi.1	⊢ 𝑁 ∈ ℕ
Assertion	nnzi	⊢ 𝑁 ∈ ℤ

Proof

Step	Hyp	Ref	Expression
1		nnzi.1	⊢ 𝑁 ∈ ℕ
2		nnssz	⊢ ℕ ⊆ ℤ
3	2 1	sselii	⊢ 𝑁 ∈ ℤ