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()

one=False
two=False
z=s.find("AB")

for i in range(z+2,len(s)-1):
    x=s[i:i+2]
    if(x=="BA"):
        one=True

z=s.find("BA")

for i in range(z+2,len(s)-1):
    x=s[i:i+2]
    # print(x)
    if(x=="AB"):
        two=True
# print(one,two)

if(one or two):
    print("YES")
else:
    print("NO")