Maximum Paired Subsequence

We are given a sequence (a_1, a_2, \ldots, a_n). A subsequence (s_1, s_2, \ldots, s_{2k}) is \textbf{paired} if and only if:

1. For every (1 \le i \le k), (s_{2i} = s_{2i-1}).
2. For every (1 \le i < k), (s_{2i} \ne s_{2i+1}).

Note that the length of any paired sequence is even.

Given a sequence (a_1, a_2, \ldots, a_n), find the maximum possible even length of a paired subsequence that can be obtained as a subsequence of the given sequence.

inputFormat

The first line contains a single integer \(n\) \(1 \le n \le 1000\), the length of the sequence.

The second line contains \(n\) space-separated integers \(a_1, a_2, \ldots, a_n\).

outputFormat

Output a single integer, the maximum even length of a paired subsequence.

sample

6
3 3 5 5 2 2

6