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.
txt = input()

txt = txt.lower()

if txt.count("ab")>0:
    txt = txt.replace("ab","")
    if txt.count("ba")>0:
        print("YES")
    else:
        print("NO")
else:
    print("NO")