while True: try: the_str = input() char_map = {} for i in range(len(the_str)): if the_str[i] not in char_map.keys(): char_map[the_str[i]] = True else: char_map[the_str[i]] = False exist = False for key, value in char_map.items(): if value == True: print(key) exist = True break if exist == False: pri...