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()
a, b = 0,0
while "AB" in s and "BA" in s:
    a += s.count("AB")
    s = s.replace("AB", "", 1)
    b += s.count("BA")
    s = s.replace("BA", "", 1)
if a > 0 and b > 0:
    print("YES")
else:
    print("NO")
# if len(s) > 100:
#     print(s)