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.
s=input()
l=[]
for i in range(len(s)-1):
    l.append(s[i]+s[i+1])
x1=[]
x2=[]
for i in range(len(l)):
    if l[i]=="AB":
        x1.append(i)
    if l[i]=="BA":
        x2.append(i)
if len(x1)==0 or len(x2)==0:
    print('NO')
else:
    if abs(x1[0]-x2[-1])!=1 or abs(x1[-1]-x2[0])!=1:
        print('YES')
    else:
        print('NO')