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.
mystr=input()
last=""
occab=False
occba=False
for i in range(0,len(mystr),1):
    if mystr[i]=="B" and mystr[i-1]=="A":
        occab=True
        mystr=mystr[:i-1]+"xx"+mystr[i+1:]
    if mystr[i]=="A" and mystr[i-1]=="B":
        occba=True
        mystr=mystr[:i-1]+"xx"+mystr[i+1:]
if occab and occba:
    print("YES")
else:
    print("NO")