num = input() new_num = [(int(i) + 3) % 9 for i in num] new_num[0], new_num[2] = new_num[2], new_num[0] new_num[1], new_num[3] = new_num[3], new_num[1] for i in new_num: print(i,end="") mainly use the feature of list to solve this problem # 其中 f 表示format [f'ch_{i}' for i in range(10)] # output [...