class Solution:    def lenLongestFibSubseq(self, A: List[int]) -> int:                s = set(A)        n = len(A)        result = 0                for i in range(n-1):            for j in range(i+1, n):                a, b = A[i], A[j]                count = 2                while a+b in s:                    a, b = b, a+b                    count += 1                    # A= [1,2,3,4,5,6,7,8]                    # [1,2,3,5,8]                     # [1,3,4,7]                     # [1,4,5]                    # ...                    # 取其中最大的序列长度                    result = max(result, count)        return result if result > 2 else 0