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()
x1=''
x2=''
p=0
for i in range(len(s)-2):
  if (s[i]=='A' and s[i+1]=='B'):
    x1=s[i]+s[i+1]
    p=i
    break
  elif(s[i]=='B' and s[i+1]=='A'):
    x1=s[i]+s[i+1]
    p=i
    break
for i in range(p+2,len(s)-1):
  if (s[i]=='B' and s[i+1]=='A'  ):
    x2=s[i]+s[i+1]
    break
  elif(s[i]=='A' and s[i+1]=='B'):
    x2=s[i]+s[i+1]
    p=i
    break
x=x1+x2
if (x=='BAAB' or x=='ABBA'):
  print('YES')
else:
  print('NO')