def clear_riddle(riddle, idea, ans):
    """
    Re-construct the riddle with user's right guess
    :param riddle: str, the latest guess result
    :param idea: str, the user's guess
    :param ans: str, the initiated random word
    :return new_riddle: str, the updated guess result
    """
    new_riddle = ''
    for i in range(len(ans)):
        if idea in ans[i]:
            # update the right guess in the right position
            new_riddle += idea
        elif str.isalpha(riddle[i]):
            # keep previous right guess
            new_riddle += riddle[i]
        else:
            # remain unsolved part
            new_riddle += '-'
    return new_riddle