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_found = False
ba_found = False
last_ab = -1
first_ba = -1

for i in range(len(s) - 1):
    if s[i:i+2] == "AB":
        ab_found = True
        last_ab = i
        if ba_found and last_ab > first_ba + 1:
            print("YES")
            exit()
    elif s[i:i+2] == "BA":
        ba_found = True
        first_ba = i
        if ab_found and first_ba > last_ab + 1:
            print("YES")
            exit()

print("NO")
