def fit_format(guess):
    """
    This function tells whether the guess input fit the format (one alphabet only)
    :param guess: str, one alphabet.
    :return: 0 or 1: 0, reject, the guess didn't fit the format; 1, pass, the guess fit the format
    """
    if len(guess) > 1:
        return 0
    else:
        if guess.isalpha():
            return 1
        else:
            return 0