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 = []
flag = 0
for i in range(len(s)-1):
    ss = s[i:i+2]
    if ss == 'AB':
        ab.append(i)
    elif ss == 'BA':
        ba.append(i)
if min(len(ab),len(ba)) == 0:
    print('NO')
else:
    ans = 'NO'
    for i in ab:
        if flag == 1:
            break
        for j in ba:
            if abs(j-i)>1:
                ans = 'YES'
                flag = 1
    print(ans)
