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Description

Original source: POJ 3630

Given $n$ digit strings, each with a length not exceeding $10$, determine whether there exist two strings $S$ and $T$ such that $S$ is a prefix of $T$. Multiple test cases are provided.

Input Format

The first line contains an integer $T$, representing the number of test cases.

For each test case, the first line contains an integer $n$, followed by $n$ lines each containing a digit string.

Output Format

For each test case, if there exist two digit strings $S$ and $T$ such that $S$ is a prefix of $T$, output NO; otherwise, output YES.

Please note the correspondence between the result and the output here!

Sample 1

2
3
911
97625999
91125426
5
113
12340
123440
12345
98346

NO
YES

Constraints and Hints

For $100\%$ of the data, $1\le T\le 40$, and $1\le n \le 10^4$.