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
s=input()
e1=re.search('AB.+BA', s)
e2=re.search('BA.+AB',s)
if (e1!=None or e2!=None):
  print('YES')
else:
  print('NO')