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.
def f(s):
    n=len(s)
    S=[]
    L=[]
    for i in range(n-1):
        if s[i]=='A' and s[i+1]=='B':
            S.append(i)
        elif s[i]=='B' and s[i+1]=='A':
            L.append(i)
    if L==[] or S==[]:
        return "NO"
    else:
        if abs(L[0]-S[0])>1 or abs(L[0]-S[-1])>1 or abs(L[-1]-S[0])>1 or abs(L[-1]-S[-1])>1:
            return "YES"
    return "NO"
x=input()
print(f(x))