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.
import re
st = input()
list_ab = [m.start() for m in re.finditer('AB', st)]
list_ba = [m.start() for m in re.finditer('BA', st)]
result_pairs = []
for num1 in list_ab:
    for num2 in list_ba:
        if abs(num1 - num2) != 1:
            result_pairs.append((num1, num2))
if len(list_ab) == 0 or len(list_ba) == 0 or len(result_pairs) == 0:
  print('NO')
elif len(result_pairs) >= 1  :
  print('YES')