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()
n = len(s)
fa = fb = la = lb = -1

# Find the first occurrence of "AB"
for i in range(n-1):
    if s[i] == 'A' and s[i+1] == 'B':
        fa = i
        break

# Find the first occurrence of "BA"
for i in range(n-1):
    if s[i] == 'B' and s[i+1] == 'A':
        fb = i
        break

# Find the last occurrence of "AB"
for i in range(n-1, 0, -1):
    if s[i] == 'A' and s[i-1] == 'B':
        la = i
        break

# Find the last occurrence of "BA"
for i in range(n-1, 0, -1):
    if s[i] == 'B' and s[i-1] == 'A':
        lb = i
        break

# Check if the non-overlapping occurrences exist
if fa != -1 and lb != -1 and abs(fa - lb) > 1:
    print("YES")
elif fb != -1 and la != -1 and abs(fb - la) > 1:
    print("YES")
else:
    print("NO")
