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()

found_AB = False
found_BA = False

for i in range(len(s) - 1):
    if s[i:i+2] == "AB" and not found_BA:
        found_AB = True
    elif s[i:i+2] == "BA" and not found_AB:
        found_BA = True

if found_AB and found_BA:
    print("YES")
else:
    print("NO")