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.

The first line contains one integer number $ n $ ( $ 2

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

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.