def solve_ab_riddle(program):
    tokens = program.split()
    
    while True:
        changed = False
        i = 0
        while i < len(tokens) - 1:
            if tokens[i] == 'A#' and tokens[i+1] == '#A':
                tokens.pop(i)
                tokens.pop(i)
                changed = True
            elif tokens[i] == 'A#' and tokens[i+1] == '#B':
                tokens[i] = '#B'
                tokens[i+1] = 'A#'
                i += 1
                changed = True
            elif tokens[i] == 'B#' and tokens[i+1] == '#A':
                tokens[i] = '#A'
                tokens[i+1] = 'B#'
                i += 1
                changed = True
            elif tokens[i] == 'B#' and tokens[i+1] == '#B':
                tokens.pop(i)
                tokens.pop(i)
                changed = True
            else:
                i += 1
        
        if not changed:
            break
    
    return ' '.join(tokens)

# Example usage
program = "B# A# #B #A B#"
result = solve_ab_riddle(program)
print(f"Original program: {program}")
print(f"Computed result: {result}")