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.
st = input()
x = st.find('AB')
y = st.find('BA')
if x + 1 == y or y + 1 == x :
  print('NO')
elif x == -1 or y == -1:
  print('NO')
else :
  print('YES')