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()
v = []
w = []
for i in range(len(s) - 1):
    if s[i:i+2] == 'AB':
        v.append(i)
    elif s[i:i+2] == 'BA':
        w.append(i)
if len(v) * len(w) == 0:
    print("NO")
else:
    if len(v) + len(w) >= 4:
        print("YES")
    elif len(v) == 1 == len(w):
        print("NO" if abs(v[0] - w[0]) == 1 else "YES")
    elif len(v) == 2:
        print("NO" if v[1] - v[0] == 2 else "YES")
    else:
        print("NO" if w[1] - w[0] == 2 else "YES")
