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()
ab = []
ba = []
for i in range(len(s) - 1):
    if s[i] == 'A' and s[i+1] == 'B': ab.append(i)
    elif s[i] == 'B' and s[i+1] == 'A': ba.append(i)
if len(ab) + len(ba) >= 4:
    print('YES')
else:
    ans = False
    for num1 in ab:
        for num2 in ba:
            if abs(num1 - num2) > 1:
                ans = True
                break
        if ans: break
    if ans: print('YES')
    else: print('NO')