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.
st = input().strip()
ab = st.find("AB")
ba = st.find("BA")
ans = False
if ab != -1:
    if ab + 2 < len(st):
        temp_ba = st[ab+2:].find("BA")

        if temp_ba != -1:
            ans = True

if ba != -1:
    if ba + 2 < len(st):
        temp_ab = st[ba+2:].find("AB")

        if temp_ab != -1:
            ans = True
    
if ans:
    print("YES")
else:
    print("NO")