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()

f1 = 0; f2 = 0
for ch in s:
    if ch == 'A':
        if f2 == 1:
            f2 = 2
            f1 *= f1 % 2 == 0
        elif f1 == 0:
            f1 = 1
    elif ch == 'B':
        if f1 == 1:
            f1 = 2
            f2 *= f2 % 2 == 0
        elif f2 == 0:
            f2 = 1
    else:
        f1 *= f1 % 2 == 0
        f2 *= f2 % 2 == 0
        
if f1 == f2 == 2:
    print("YES")
else:
    print("NO")
        