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()

if len(s) < 4:
    print("NO")
else:
    found = False
    for i in range(len(s)-1):
        if s[i:i+2] == "AB":
            if "BA" in s[i+2:]:
                found = True
                break
        elif s[i:i+2] == "BA":
            if "AB" in s[i+2:]:
                found = True
                break

    if found:
        print("YES")
    else:
        print("NO")
