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.
a = []
b = []
def sol(s):
    for i in range(0, len(s) - 1):
        if s[i: i + 2] == "AB":
            a.append(i)
        elif s[i: i + 2] == "BA":
            b.append(i)
s = input().strip()
sol(s)

for i in a:
    for j in b:
        if j != i + 1 and i != j + 1:
            print("YES")
            exit()
print("NO")  