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()

first_ab, first_ba, last_ab, last_ba = -1, -1, -1, -1
for i in range(len(s) - 1):
  if s[i] == 'A' and s[i + 1] == 'B':
    if first_ab == -1:
      first_ab = i
    last_ab = i
  if s[i] == 'B' and s[i + 1] == 'A':
    if first_ba == -1:
      first_ba = i
    last_ba = i
if first_ab == -1 or first_ba == -1:
  print("NO")
else:
  if last_ba > first_ab + 1 or last_ab > first_ba + 1:
    print("YES")
  else:
    print("NO")
