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()
x = S.find("AB")
y = S.find("BA")
# print(x, y)
if x == -1 or y == -1:
    print("NO")

elif x + 1 != y and y + 1 != x:
    print("YES")
else:
    print("NO")
