求教 Python 练习，单词排序

题目如下

Exercise 5. Write a program words.py. The program should repeatedly ask the user to enter a word, one at a time, until they enter done (which does not count as an entered word). At that point, the program should print: [first] comes first in the dictionary [last] comes last in the dictionary with [first] and [last] replaced with entered words which would come first and last when sorted alphabetically. You can assume all words entered are lower-case, and don’t contain non-alphabetic characters. You can also assume that the user will always give at least one word (different than done). An example session might look as follows: Enter a word: foo Enter a word: bar Enter a word: baz Enter a word: zoo Enter a word: boo Enter a word: done bar comes first in the dictionary zoo comes last in the dictionary

我自己弄了一个， i='a' j='z' while True: x=input('Enter a word: ') if x =='done': break if str(x)>=i: i=x continue if str(x)<j: j=x continue print(j, 'comes first in the dictionary') print(i, 'comes last in the ditionary')

但是这有个问题，就是只输入一个单词的时候就废了。。。 有没有大佬出来指点一下？给点思路。。。但是不要用太高级的，我目前只学到 flow control，这是老师留的作业题，太高级的我也不会用