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()
b=[]
c=[]
for d in range(len(a)-1):
    if a[d:d+2]=="AB":b.append(d)
    elif a[d:d+2]=="BA":c.append(d)
if len(b)==0 or len(c)==0:print("NO")
elif abs(min(b)-max(c))>1 or abs(max(b)-min(c))>1:print('YES')
else:print("NO")