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()

ab = False
ba = False

i = 0
while i + 1 < len(s):
    if not ab and s[i] == "A" and s[i + 1] == "B":
        ab = True
        i += 2
        continue

    if not ba and s[i] == "B" and s[i + 1] == "A":
        ba = True
        i += 2
        continue
    i += 1

if (ab and ba):
    print("YES")
else:
    print("NO")