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()
n = len(s)
found_ab = found_ba = False
ab_pos = ba_pos = -1

for i in range(n-1):
    if s[i:i+2] == 'AB':
        if found_ab:
            ba_pos = i
            break
        else:
            ab_pos = i
            found_ab = True
    elif s[i:i+2] == 'BA':
        if found_ba:
            ab_pos = i
            break
        else:
            ba_pos = i
            found_ba = True

if found_ab and found_ba and abs(ab_pos - ba_pos) > 1:
    print("YES")
else:
    print("NO")
