Solve the programming task below in a Python markdown code block.
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You are given a string $S$ with length $N$. Determine if it is possible to find two non-empty strings $A$ and $B$ which satisfy the following conditions:
$A + B = S$, where $+$ denotes string concatenation
$B$ is a substring of $A$

Note: $B$ is a substring of $A$ if $B$ can be obtained from $A$ by deleting several (possibly zero) characters from the beginning and several (possibly zero) characters from the end. For example, "ab" is a substring of "cabd", but "ad" is not.

------  Input ------
The first line of the input contains a single integer $T$ denoting the number of test cases. The description of $T$ test cases follows.
The first line of each test case contains a single integer $N$.
The second line contains a single string $S$.

------  Output ------
For each test case, print a single line containing the string "YES" if it is possible to find strings $A$ and $B$ satisfying the given conditions or "NO" otherwise (without quotes).

------  Constraints ------
$1 ≤ T ≤ 10^{4}$
$2 ≤ N ≤ 10^{5}$
$|S| = N$
$S$ contains only lowercase English letters
the sum of $N$ over all test cases does not exceed $10^{6}$

----- Sample Input 1 ------ 
5

6

cabdab

21

yourcrushlovesyouback

16

wubbalubbadubdub

5

split

7

splitit
----- Sample Output 1 ------ 
YES

NO

YES

NO

YES
----- explanation 1 ------ 
Example case 1: We can choose "cabd" as $A$ and "ab" as $B$. We can see that $A + B = S$ and $B$ is a substring of $A$.

Example case 2: It is impossible to find two strings which satisfy the constraints. For example, when $A$ is "yourcrushlovesyou" and $B$ is "back", then $A + B = S$, but $B$ is not a substring of $A$.

Example case 3: We can choose "wubbalubbadub" as $A$ and "dub" as $B$.