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()
s1=0
s2=0
if len(s)%2==0:
    for i in range(0,len(s),2):
        if s[i]+s[i+1]=="AB":
            s1+=1
        elif s[i]+s[i+1]=="BA":
            s2+=1
else:
    for i in range(0,len(s)-1,2):
        if s[i]+s[i+1]=="AB":
            s1+=1
        elif s[i]+s[i+1]=="BA":
            s2+=1
if s1>0 and s2>0:
    print("YES")
else:
    print("NO")