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()
AB = False
BA = False
prev = ""
i = 0
while i < len(s) - 1:
    
    if s[i] + s[i + 1] == "AB" and not AB:

        AB = True
        i += 2
    elif s[i] + s[i + 1] == "BA" and not BA:
        BA = True
        i += 2
    else:
        i += 1

if AB and BA:
    print("YES")
    exit()
else:
    AB = BA = False

while i < len(s) - 1:
    
    if s[i] + s[i + 1] == "BA" and not BA:

        AB = True
        i += 2
    elif s[i] + s[i + 1] == "AB" and not AB:
        BA = True
        i += 2
    else:
        i += 1

if AB and BA:
    print("YES")


else:
    print("NO")
    
    
    