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=input()
q=0
if("AB" in a):
    p=a.index("AB")
    if("BA" in a[p+2:]):
        q=1
if(q==0):
    if("BA" in a):
        p=a.index("BA")
        if("AB" in a[p+2:]):
            q=1
if(q==1):
    print("YES")
else:
    print("NO")
        

        