B'You are given a string s consisting of lowercase Latin characters. In an operation, you can take a character and replace all occurrences of this character with texttt{0} or replace all occurrences of this character with texttt{1} . Is it possible to perform some number of moves so that the resulting string is an alternating binary string ^{ dagger} ? For example, consider the string texttt{abacaba} . You can perform the following moves: ^{ dagger} An alternating binary string is a string of texttt{0} s and texttt{1} s such that no two adjacent bits are equal. For example, texttt{01010101} , texttt{101} , texttt{1} are alternating binary strings, but texttt{0110} , texttt{0a0a0} , texttt{10100} are not. The input consists of multiple test cases. The first line contains an integer t ( 1 <= q t <= q 100 ) -- the number of test cases. The description of the test cases follows. The first line of each test case contains an integer n ( 1 <= q n <= q 2000 ) -- the length of the string s . The second line of each test case contains a string consisting of n lowercase Latin characters -- the string s . For each test case, output "YES" (without quotes) if you can make the string into an alternating binary string, and "NO" (without quotes) otherwise. You can output the answer in any case (for example, the strings "yEs", "yes", "Yes" and "YES" will be recognized as a positive answer). The first test case is explained in the statement. In the second test case, the only possible binary strings you can make are texttt{00} and texttt{11} , neither of which are alternating. In the third test case, you can make texttt{1} , which is an alternating binary string. '...