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()
l = []
for i in range(len(s)-1):
    if s[i] == 'a' and s[i+1] == 'b':
        for j in range(i+1,len(s)-1):
            if j!=i:
                if s[j] == 'b' and s[j+1] == 'a':
                    l.append('YES')
                else:
                    l.append('NO')
    if s[i] == 'b' and s[i+1] == 'a':
        for j in range(i+1,len(s)-1):
            if j!=i:
                if s[j] == 'a' and s[j+1] == 'b':
                    l.append('YES')
                else:
                    l.append('NO')
    else:
        l.append('NO')
if 'YES' in l:
    print('YES')
else:
    print('NO')
    