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.
t = input()
i = 0
foundAB = False
foundBA = False
while i < len(t)-1:
    if not foundAB and t[i:i+2] == 'AB':
        foundAB = True
        i += 1
    elif not foundBA and t[i:i+2] == 'BA':
        foundBA = True
        i += 1
    i += 1
if foundBA and foundAB:
    print("YES")
else:
    print("NO")