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=[],[]
V,B=[],[]
for i in range(len(c)-1):
    if c[i]+c[i+1]=="AB":
        m+=[i+1]
        B+=[i]
    if c[i]+c[i+1]=="BA":
        n+=[i]
        V+=[i+1]
if (set(n).symmetric_difference(set(m))) and set(V).symmetric_difference(set(B)) and n and m:
    print("YES")
else:
    print("NO")