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()
n = len(s)
if "AB" not in s or "BA" not in s:
    print("NO")
    exit(0)
start = s.index("AB") + 2
flag = False
for i in range(start, n - 1):
    if s[i:i + 2] == "BA":
        flag = True
        break
if flag:
    print("YES")
    exit(0)
start = s.index("BA") + 2
flag = False
for i in range(start, n - 1):
    if s[i:i + 2] == "AB":
        flag = True
        break
if flag:
    print("YES")
else:
    print("NO")