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# 1050 PHONE LIST

By Martha Woods,2014-01-15 19:53
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1050 PHONE LIST

Phone List

时间限制;5000 ms | 内存限制;65536 KB

描述

Given a list of phone numbers, determine if it is consistent in the sense that no number is

the prefix of another.

Lets say the phone catalogue listed these numbers:

Emergency 911

Alice 97 625 999

Bob 91 12 54 26

In this case, its not possible to call Bob, because the central would direct your call to the

emergency line as soon as you had dialled the first three digits of Bobs phone number. So this list would not be consistent.

输入

The first line of input gives a single integer, 1 ? t ? 40, the number of test cases. Each test

, the number of phone numbers, on a separate line, 1 ? ? 10000. case starts with nn

Then follows n lines with one unique phone number on each line. A phone number is a

sequence of at most ten digits.

输出

For each test case, output YES if the list is consistent, or NO otherwise.

样例输入

2

3

911

97625999

91125426

5

113

12340

123440

12345

98346

样例输出

NO

YES

Nordic Collegiate Programming Contest 2007

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