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.
a=list(input())
fg,gf=0,0
for i in range(len(a)-1):
    if a[i]=='A':
        if a[i+1]=='B':
            fg=1
            a[i+1]='F'
            a[i]='G'
            break
if fg:
    for i in range(len(a)-1):
        if a[i]=='B':
            if a[i+1]=='A':
                gf=1
                a[i+1]='F'
                a[i]='G'
                break
if fg and gf:
    print("YES")
else:
    print("NO")