Python Solution
\nclass Solution:\n    def strWithout3a3b(self, A, B):\n        """\n        :type A: int\n        :type B: int\n        :rtype: str\n        """\n\n        def
```\nclass Solution:\n    def strWithout3a3b(self, A, B):\n        """\n        :type A: int\n        :type B: int\n        :rtype: str\n        """\n\n        def rec(A,B):\n            if B == 0:\n                return a*A\n            if A == B:\n                return (b+a)*A\n            elif A - B >= 2:\n                return a*2 + b + rec(A-2,B-1)\n            else:\n                return a + rec(A-1,B)\n\n        a, b = \'a\', \'b\'\n        if A < B:\n            A, B = B, A\n            a, b = \'b\', \'a\'\n        return rec(A,B)\n```
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