COMP2041

21T2 Q10 — 删除不平衡的词

把 stdin 复制到 stdout，但删除不平衡的词。词平衡指其中每个字符恰好出现 n 次（某个 n）；忽略大小写。词是任意非空白串（故 tock-tock 是一个词）。保留的词用单个空格分隔；保持行数。

例：Gaga 平衡（g×2, a×2）；gauge 不平衡。

Python only; no external programs / subprocess. From COMP2041/9044 21T2 Final.

样例

stdin

I shall be telling this with a sigh
Somewhere ages and ages hence:
Two roads diverged in a wood, and I --
I took the one less traveled by,
And that has made all the difference.

期望输出

I be this with a sigh
ages and ages
Two roads in a and I --
I the one by,
And has made the

python3