while True:
    try:
        want_list = list(input())
        char_list = list(set(want_list))
        
        temp_list = []
        for each_char in char_list:
            temp_list.append(want_list.count(each_char))
        min_count = min(temp_list)
        
        min_char_list = []
        for each_char in char_list:
            if want_list.count(each_char) == min_count:
                min_char_list.append(each_char)
        
        new_list = []
        for index in range(0, len(want_list)):
            if want_list[index] not in min_char_list:
                new_list.append(want_list[index])
        
        res = "".join(new_list)
        print(res)
    except EOFError:
        break