A15662. Notepad#

You want to type the string $s$ , consisting of $n$ lowercase Latin letters, using your favorite text editor Notepad#.

Notepad# supports two kinds of operations:

- append any letter to the end of the string;
- copy a continuous substring of an already typed string and paste this substring to the end of the string.

Can you type string $s$ in strictly less than $n$ operations?

The first line contains a single integer $t$ ( $1 \le t \le 10^4$ ) — the number of testcases.

The first line of each testcase contains a single integer $n$ ( $1 \le n \le 2 \cdot 10^5$ ) — the length of the string $s$ .

The second line contains a string $s$ , consisting of $n$ lowercase Latin letters.

The sum of $n$ doesn't exceed $2 \cdot 10^5$ over all testcases.

For each testcase, print "YES" if you can type string $s$ in strictly less than $n$ operations. Otherwise, print "NO".

In the first testcase, you can start with typing "codef" ( $5$ operations), then copy "o" ( $1$ operation) from an already typed part, then finish with typing "rces" ( $4$ operations). That will be $10$ operations, which is not strictly less than $n$ . There exist other ways to type "codeforces". However, no matter what you do, you can't do less than $n$ operations.

In the second testcase, you can type "labac" ( $5$ operations), then copy "aba" ( $1$ operation), finishing the string in $6$ operations.