k >=0 or k< (1/3)(1-ㅠ/2): 0개
(1/3)(루트3- 2ㅠ/3) <= k <0  or k=(1/3)(1-ㅠ/2): 1개
(1/3)(1-ㅠ/2) < k < (1/3)(루트3- 2ㅠ/3) :2개

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