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()
x=0;y=0
for i in range(len(s)-1):
    if s[i]=='A' and s[i+1]=='B':
        x=1
        i+=1
    elif s[i]=='B' and s[i+1]=='A':
        y=1
        i+=1
print("YES" if x+y==2 else "NO")