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.
b=input()
d=[]
for i in range(len(b)-1):
    z=b[i]+b[i+1]
    d.append(z)
if "AB" and "BA" not in d:
    print("NO")
else:
    t=list(d).index("AB")
    INDICES=[i for i, x in enumerate(d) if x=="BA"]
    f=max(INDICES)
    if t+1==f or f+1==t:
        print("NO")
    else:
        print("YES") 