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.
ch = input()
found = False

# Check for "AB" followed by "BA"
if "AB" in ch and ch.index("AB") < len(ch) - 1:
    index = ch.index("AB") + 2
    if "BA" in ch[index:]:
        found = True

# Check for "BA" followed by "AB"
if "BA" in ch and ch.index("BA") < len(ch) - 1:
    index = ch.index("BA") + 2
    if "AB" in ch[index:]:
        found = True

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