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CF1324B.Yet Another Palindrome Problem
Yet Another Palindrome Problem
You are given an array consisting of integers.
Your task is to determine if has some subsequence of length at least that is a palindrome.
Recall that an array is called a subsequence of the array if can be obtained by removing some (possibly, zero) elements from (not necessarily consecutive) without changing the order of remaining elements. For example, , and are subsequences of , but and are not.
Also, recall that a palindrome is an array that reads the same backward as forward. In other words, the array of length is the palindrome if for all from to . For example, arrays , , and are palindromes, but arrays and are not.
You have to answer independent test cases.
Input
The first line of the input contains one integer () — the number of test cases.
Next lines describe test cases. The first line of the test case contains one integer () — the length of . The second line of the test case contains integers (), where is the -th element of .
It is guaranteed that the sum of over all test cases does not exceed ().
Output
For each test case, print the answer — "YES" (without quotes) if has some subsequence of length at least that is a palindrome and "NO" otherwise.
Note
In the first test case of the example, the array has a subsequence which is a palindrome.
In the second test case of the example, the array has two subsequences of length which are palindromes: and .
In the third test case of the example, the array has no subsequences of length at least which are palindromes.
In the fourth test case of the example, the array has one subsequence of length which is a palindrome: (and has two subsequences of length which are palindromes: both are ).
In the fifth test case of the example, the array has no subsequences of length at least which are palindromes.
Samples
5
3
1 2 1
5
1 2 2 3 2
3
1 1 2
4
1 2 2 1
10
1 1 2 2 3 3 4 4 5 5
YES
YES
NO
YES
NO
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