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.
def f(s):
    L=list(s)
    xx=True
    yy=True
    n=len(L)
    i=0
    while i<n and (xx or yy):
        if L[i]=='A' and L[i+1]=='B' and xx:
            x=i
            xx=False
        if  L[i]=='B' and L[i+1]=='A' and yy:
            y=i
            yy=False
        i+=1
    if abs(x-y)>=2:
        return "YES"
    return "NO"
x=input()
print(f(x))