while True:
    try:
        str_ = input()
        dict_ = {}
        res = ''
        for s in str_:
            if s not in dict_.keys():
                dict_[s] = 1
            else:
                dict_[s] += 1
        min_ = min(dict_.values())
        for s in str_:
            if dict_[s] != min_:
                res += s
        print(res)
    except:
        break