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()
ans = None
if "AB" in s: 
    s_ = s[0:s.index("AB")] + 'XX' + s[s.index("AB") + 2:]
    if "BA" in s_: ans = True; print("YES")
    else: ans = False
if not ans:
    if "BA" in s: 
        s_ = s[0:s.index("BA")] +'XX'+ s[s.index("BA") + 2:]
        if "AB" in s_: ans = True; print("YES")
        else: ans = False
if not ans: print ("NO")
