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()

a0 = s.find("AB")
a1 = len(s) - s[::1].find("BA") - 1

b0 = s.find("BA")
b1 = len(s) - s[::1].find("AB") - 1

if a0 == -1 or b0 == -1:
    print("NO")
else if a0 + 1 < b1 or b0 + 1 < a1:
    print("YES")
else:
    print("NO")
