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.
word=input()
n1=[]
n2=[]
bool=False
for i in range(len(word)-1):
    if word[i]+word[i+1]=="AB":
        n1.append(i)
    if word[i]+word[i+1]=="BA":
        n2.append(i)
for j in n1:
    for m in n2:
        if abs(j-m)>=2:
            bool=True
            break    
if bool:
    print("YES")
else:
    print("NO")