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().casefold()
found = False

# Check for "AB" followed by "BA"
for i in range(len(s) - 1):
    if s[i:i+2] == 'ab':
        for j in range(i + 2, len(s) - 1):
            if s[j:j+2] == 'ba':
                found = True
                break

    if found:
        break

# Check for "BA" followed by "AB" if not found yet
if not found:
    for i in range(len(s) - 1):
        if s[i:i+2] == 'ba':
            for j in range(i + 2, len(s) - 1):
                if s[j:j+2] == 'ab':
                    found = True
                    break

    if found:
        break

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