D. Fibonacci-ishtime limit per test3 secondsmemory limit per test512 megabytesinputstandard inputoutputstandard outputYash has recently learnt about the Fibonacci sequence and is very excited about it. He calls a sequence Fibonacci-ish if   the sequence consists of at least two elements  f0 and f1 are arbitrary  fn + 2 = fn + 1 + fn for all n ≥ 0. You are given some sequence of integers a1, a2, ..., an. Your task is rearrange elements of this sequence in such a way that its longest possible prefix is Fibonacci-ish sequence.InputThe first line of the input contains a single integer n (2 ≤ n ≤ 1000) — the length of the sequence ai.The second line contains n integers a1, a2, ..., an (|ai| ≤ 109).OutputPrint the length of the longest possible Fibonacci-ish prefix of the given sequence after rearrangement.ExamplesInput31 2 -1Output3Input528 35 7 14 21Output4NoteIn the first sample, if we rearrange elements of the sequence as  - 1, 2, 1, the whole sequence ai would be Fibonacci-ish.In the second sample, the optimal way to rearrange elements is , , , , 28.
Input31 2 -1
Output3
['brute force', 'dp', 'hashing', 'implementation', 'math', '*2000']