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CF1796A.Typical Interview Problem
Typical Interview Problem
The FB-string is formed as follows. Initially, it is empty. We go through all positive integers, starting from , in ascending order, and do the following for each integer:
- if the current integer is divisible by , append
Fto the end of the FB-string; - if the current integer is divisible by , append
Bto the end of the FB-string.
Note that if an integer is divisible by both and , we append F, and then B, not in the opposite order.
The first characters of the FB-string are FBFFBFFBFB: the first F comes from the integer , the next character (B) comes from , the next F comes from the integer , and so on. It's easy to see that this string is infinitely long. Let be the -th character of FB-string; so, is F, is B, is F, is F, and so on.
You are given a string , consisting of characters F and/or B. You have to determine whether it is a substring (contiguous subsequence) of the FB-string. In other words, determine if it is possible to choose two integers and () so that the string is exactly .
For example:
FFBis a substring of the FB-string: if we pick and , the string is exactlyFFB;BFFBFFBFis a substring of the FB-string: if we pick and , the string is exactlyBFFBFFBF;BBBis not a substring of the FB-string.
Input
The first line contains one integer () — the number of test cases.
Each test case consists of two lines. The first line contains one integer () — the number of characters in . The second line contains , which is a string of exactly characters. Each character of is either F or B.
Output
For each test case, print YES if is a substring of the FB-string, or NO otherwise.
You may print each letter in any case (YES, yes, Yes will all be recognized as positive answer, NO, no and nO will all be recognized as negative answer).
Samples
3
3
FFB
8
BFFBFFBF
3
BBB
YES
YES
NO
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