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().lower()+"ghjkl"
ab = 0
ba = 0
aba = 0
for i in range(len(s)-5):
    if s[i] == "a" and s[i+1] == "b":
        ab+=1
        if s[i+2] == "a":
            aba+=1
    if s[i] == "b" and s[i+1] == "a":
        ba+=1
        if s[i+2] == "b":
            aba+=1
if ab*ba == 0:
    print("NO")
    exit()
elif ab*ba > 1:
    print("YES")
    exit()
elif aba == 0:
    print("YES")
    exit()
else:
    print("NO")
    exit()