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.
s = input()
l = ["AB","BA"]
i = 0
while i<(len(s)-1):
    if len(l)==0:
        break
    if s[i]!='A' and s[i]!='B':
        continue
    elif s[i]=='A'and s[i+1]=='B':
        i+=2
        l.remove("AB")
    elif s[i]=='B'and s[i+1]=='A':
        i+=2
        l.remove("BA")
if len(l)==0:
    print('YES')
else:
    print('NO')