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()
n = len(s)
c = 0
for i in range(n):
  if i != n-1:
    if (s[i] == "A" and s[i+1] == "B") or (s[i] == "B" and s[i+1] == "A"):
      c += 1
      i += 1
  if c > 2:
    print("NO")
    break
if c == 2:
  print("YES")