SPOJ Problem Set (classical)
4033. Phone List
Problem code: PHONELST

Phone List
Given a list of phone numbers, determine if it is consistent in the
sense that no number is the prefix of another. Let’s say the phone
catalogue listed these numbers:
• Emergency 911
• Alice 97 625 999
• Bob 91 12 54 26
In this case, it’s 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 Bob’s phone number. So this list would not be
consistent.
Input
The first line of input gives a single integer, 1 <= t <= 40, the number of test cases. Each
test case starts with n, the number of phone numbers, on a separate line, 1 <= n <= 10000.
Then follows n lines with one unique phone number on each line. A phone number is a sequence of at most ten digits.
Output
For each test case, output “YES” if the list is consistent, or “NO” otherwise.
Example
Input:
2
3
911
97625999
91125426
5
113
12340
123440
12345
98346
Output:
NO
YES
