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, BA = set(), set()
for i in range(len(s)-1):
    if s[i] == 'A' and s[i+1] == 'B':
        AB.add(i)
        continue
    if s[i] == 'B' and s[i+1] == 'A':
        BA.add(i)
if len(AB) == 0 or len(BA) == 0:
    print("NO")
else:
    ans = "NO"
    found = False
    for ab in AB:
        if found: break
        for ba in BA:
            if ab+1 == ba or ab-1 == ba:
                continue
            else:
                found = True
                ans = "YES"
                break
    print(ans)