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.
a = list(input())
k = False
k1 = False
i = 0

while i < len(a):
    if a[i:i+2] == ['B', 'A']:
        k = True
        a[i] = '/'
        a[i+1] = '/'
        break
    i += 1
i = 0
while i < len(a):
    if a[i:i+2] == ['A', 'B']:
        k1 = True
        a[i] = '/'
        a[i+1] = '/'
        break
    i += 1

if k == True and k1 == True:
    print('YES')
else:
    print('NO')
