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()
s += "  "
n = len(s)
c1 = 0
c2 = 0
i = 0
while i<n:
  flag = 0
  if (s[i] == "A" and s[i+1] == "B"):
    c1 += 1
    i += 2
    flag = 1
  elif s[i] == "B" and s[i+1] == "A" and flag == 0:
    c2 += 1
    i += 2
    flag = 1
  if flag == 0:
    i += 1
if c1 >= 1 and c2 >= 1:
  print("YES")
else:
  print("NO")