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()
a=''
b=''
x=''
if len(s)<=3:
  print('NO')
  a=0
  b=0
else:
  a=s.find('AB')
  b=s.find('BA')
  c=s.find('A', a+1)
  d=s.find('B',b+1)
  if 'BABA' in s and s!='BABA':
    x='ABBA'
  else:
    if (b-1!=a or a-1!=b or c!=b+1 or d!=a+1):
      x=s[a:a+2]+s[b:b+2]
  if x in ['BAAB','ABBA']:
    print('YES')
  else:
    print('NO')
