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();lenn=len(s)
count_1=0;count2=0
for i in range(lenn-1):
    if s[i]=="A" and s[i+1]=="B" :
        if i==lenn-2:count_1+=1
        else:
            if s[i+2]!="A":count_1+=1
    elif s[i]=="B" and s[i+1]=="A":
        if i==lenn-2:count2+=1
        else:
            if s[i+2]!="B":count2+=1
if count_1*count2==0:print("NO")
else:print("YES")