CF813D.Two Melodies

Alice is a beginner composer and now she is ready to create another masterpiece. And not even the single one but two at the same time!

Alice has a sheet with n notes written on it. She wants to take two such non-empty non-intersecting subsequences that both of them form a melody and sum of their lengths is maximal.

Subsequence is a sequence that can be derived from another sequence by deleting some elements without changing the order of the remaining elements.

Subsequence forms a melody when each two adjacent notes either differs by 1 or are congruent modulo 7.

You should write a program which will calculate maximum sum of lengths of such two non-empty non-intersecting subsequences that both of them form a melody.

爱丽丝是一位初出茅庐的作曲家，现在她准备创作另一部杰作——而且不是一首，而是同时创作两首！

爱丽丝有一张乐谱，上面写有 $n$ 个音符。她希望从中选出两个非空、互不相交的子序列，使得这两个子序列各自都构成一段旋律，且它们的长度之和最大。

子序列是指从原序列中删除若干元素（可为零个）后，保持剩余元素相对顺序不变所得到的序列。

当子序列中每两个相邻音符的差的绝对值为 1，或二者模 7 同余时，该子序列构成一段旋律。

你需要编写一个程序，计算满足上述条件的两个非空、互不相交子序列的最大长度之和。

The first line contains one integer number n (2 ≤ n ≤ 5000).

The second line contains n integer numbers _a_1, _a_2, ..., a__n (1 ≤ a__i ≤ 105) — notes written on a sheet.

第一行包含一个整数 $ n $（$ 2 \leq n \leq 5000 $）。

第二行包含 $ n $ 个整数 $ a_1, a_2, \dots, a_n $（$ 1 \leq a_i \leq 10^5 $）——写在纸上的音符。

Print maximum sum of lengths of such two non-empty non-intersecting subsequences that both of them form a melody.

输出满足以下条件的两个非空、不相交子序列的最大长度之和：这两个子序列各自均构成一段旋律。

In the first example subsequences [1, 2] and [4, 5] give length 4 in total.

In the second example subsequences [62, 48, 49] and [60, 61] give length 5 in total. If you choose subsequence [62, 61] in the first place then the second melody will have maximum length 2, that gives the result of 4, which is not maximal.

在第一个例子中，子序列 [1, 2] 和 [4, 5] 的总长度为 4。

在第二个例子中，子序列 [62, 48, 49] 和 [60, 61] 的总长度为 5。若首先选择子序列 [62, 61]，则第二段旋律的最大长度为 2，结果为 4，这不是最大值。