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.
c=input()
n,m=0,0
for i in range(len(c)-1):
    if c[i]+c[i+1]=="AB" and n==0:
        n+=1
        g=i+1
    if c[i]+c[i+1]=="BA" and m==0:
        m+=1
        gg=i+1
    if n:
        if c[i]+c[i+1]=="BA" and i!=g:
            print("YES")
            break
    if m:
        if c[i]+c[i+1]=="AB" and i!=gg:
            print("YES")
            break
else:
    print("NO")
