def is_choku(s):
    if (s == ''):
        return True
    if ((len(s) >= 1) and (s[(- 1)] in choku_tail) and is_choku(s[:(- 1)])):
        return True
    if ((len(s) >= 2) and (s[(- 2):] in choku_tail) and is_choku(s[:(- 2)])):
        return True
    return False
def is_choku(s):
    if (s == ):
        return True
    if ((len(s) >= 1) and (s[(- 1)] in choku_tail) and is_choku(s[:(- 1)])):
        return True
    if ((len(s) >= 2) and (s[(- 2):] in choku_tail) and is_choku(s[:(- 2)])):
        return True
    return False