num=input() # 1.遍历字符串。如果是小写字母或者大写字母,str1加进去。否则加" " str1=" " for i in num: if (i>='a' and i<='z') or (i>='A' and i<='Z'): str1=str1+i else: str1=str1+" " # 2.按照" "分割成list的元素 list2=str1.split(" ") # 3.list倒序 list2=list2[::-1] # 4.遍历list,输出元素,并且以" "结尾 for i in list2: print(i,end=" ")