python3简单解法

while True:
    try:
        s = input()
        for i in s:
            if not i.isalpha():                
                s = s.replace(i, ' ')#replace替换字符串需要赋值到新的字符串
        lst1 = s.split(' ')
        res = lst1[::-1]
        for i in res:
            print(i,end=' ')
    except:
        break