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().upper()
b = list(a)

ans = []
if 'AB' in a and 'BA' in a:
    for i in range(len(b) - 1):
        if b[i] == 'A' and b[i + 1] == 'B':
            ans.append(i)
            ans.append(i + 1)
        elif b[i] == 'B' and b[i + 1] == 'A':
            ans.append(i)
            ans.append(i + 1)
    r = set(ans)
    if len(ans) == len(r):
        print('YES')
    else:
        print('NO')
else:
    print('NO')