Fibonacci-ish

3000ms

524288K

Description:

Yash 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
f_n + 2 = f_n + 1 + f_n for all n ≥ 0.

You are given some sequence of integers a₁, a₂, ..., a_n. Your task is rearrange elements of this sequence in such a way that its longest possible prefix is Fibonacci-ish sequence.

Input:

The first line of the input contains a single integer n (2 ≤ n ≤ 1000) — the length of the sequence a_i.

The second line contains n integers a₁, a₂, ..., a_n (|a_i| ≤ 10⁹).

Output:

Print the length of the longest possible Fibonacci-ish prefix of the given sequence after rearrangement.

Sample Input:

3
1 2 -1

Sample Output:

Sample Input:

5
28 35 7 14 21

Sample Output:

Note:

In the first sample, if we rearrange elements of the sequence as - 1, 2, 1, the whole sequence a_i would be Fibonacci-ish.

In the second sample, the optimal way to rearrange elements is $\text{[math]}$ , $\text{[math]}$ , $\text{[math]}$ , $\text{[math]}$ , 28.

Informação

Provedor Codeforces

Código CF633D