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()
f = 0
a = set()
for i in range(len(s)-1):
    if s[i:i+2] == "AB":
        a.add(i+1)
for i in range(len(s)-1):
    if s[i:i+2] == "BA":
        if (i in a) and len(a) == 1:
            continue
        else:
            if len(a):
                f = 1
print("YES" if f else "NO")
