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.
a = input()
t = False
t1 = False
i = 1
while i < len(a):
    if t1 and a[i - 1] + a[i] == "BA":
        t = True
    if a[i - 1] + a[i] == "AB" and not t1:
        t1 = True
        i += 1
    i += 1
t1 = False
i = 1
while i < len(a):
    if t1 and a[i - 1] + a[i] == "AB":
        t = True
    if a[i - 1] + a[i] == "BA" and not t1:
        t1 = True
        i += 1
    i += 1
print("YES" if t else "NO")
