python统计wenben.txt出现次数最少的单词？

以及对应的出现次数，并统计这类单词有多少个，，，，还有思路是怎样的？

from collections import Counter

txt_path="wenben.txt"
document=''
with open(txt_path,'r') as f:
    for i in f.readlines():
        document+=i
word_counter = Counter(document)
#输出观察下
print(word_counter)