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a(a|b)*a|b(a|b)*b|a|bStarts and ends with the same characterClassic ProblemsFormal RE✨ Emoji Combos

Length-1 strings trivially satisfy this. For length ≥ 2, the first and last characters must match.

✓ Accepts
abaabbababababba
✗ Rejects
abbaaabbbaε
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