You are given string *s*. Your task is to determine if the given string *s* contains two non-overlapping substrings "AB" and "BA" (the substrings can go in any order).
The only line of input contains a string *s* of length between 1 and 10<sup class="upper-index">5</sup> consisting of uppercase Latin letters.
a = input()
ab = a.find('AB')
s = a[:ab] + a[ab+2:]
ba = s.find('BA')
ab1 = a.rfind('AB')
s1 = a[:ab1] + a[ab1+2:]
ba1 = a.rfind('BA')
if (ba != -1 and ab != -1) or (ba1 != -1 and ab1 != -1):
    print('YES')
else:
    print('NO') 
    
    