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=len(s)
flag=False
for i in range(l-1):
    if s[i:i+2]=="AB":
        flag=True
        check="BA"
        break
    elif s[i:i+2]=="BA":
        flag=True
        check="AB"
        break
if flag==False:
    print("NO")
else :
    flag=False
    for j in range(i+2,l-1):
        if s[j:j+2]==check:
            flag=True
    if flag==True:
        print("YES")
    else :
        print("NO")