Guess the missing item from this list: α-3, α-0, β-4, β-1, α-1, α-4, β-5, α-5, α-2, β-6, α-8, α-7, α-6, β-0, β-3, β-2.
Directly answer with only one item. Item format should match the list format. Provide no explanation. Answer format: "{item}."