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.
word = input()
try:
    if (abs(word.index('AB') - word.index('BA'))) >=2:
        print("YES")
    else:
        print("NO")
except:
    print('NO')