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.
# Wadea #

s = list(input())
r = 0
m = 0
for i in range(len(s)-1):
    if s[i] == "A" and s[i+1] == "B":
        r += 1
        s[i] = ""
        s[i+1] = ""
        break
    elif s[i] == "B" and s[i+1] == "A" and m == 0:
        r += 1
        s[i] = ""
        s[i+1] = ""
        m = 1
        break
for j in range(len(s)-1):
    if s[j] == "B" and s[j+1] == "A" and m == 0:
        r += 1
        s[j] = ""
        s[j+1] = ""
        break
    elif s[j] == "A" and s[j+1] == "B":
        r += 1
        s[j] = ""
        s[j+1] = ""
        break
if r == 2:
    print("YES")
else:
    print("NO")