过滤无用词汇程序。规则如下：

1. 能接受的字符是：字母 数字 标点符号 , . " 还有无用的符号 @#￥

2. 对于敏感信息的词语是不分大小写的。

3. 要注意滤去可能在敏感词汇的中间出现的一些空格（比如要滤去lv, 输入l v时要辨认出来并滤去）。

4. 若有用信息（字母，数字）中间夹这无用信息（非字母，数字，标点符号），也要辨认出并滤去。假如敏感词汇是mz, 那么输入 m &# z也要滤去,但是输入 m1，z不用滤去。



现在要过滤的信息有L4和 Fd和D26这3个词，而且接受输入的字符串长度为20个字符。

-Filter useless vocabulary program.Rules are as follows:

Acceptable characters are: alphanumeric punctuation. "Useless symbols @# ￥

2 words for sensitive information is not case sensitive.

To pay attention to filter out some of the spaces may appear in the middle of the sensitive words (such as filtered lv, lv when the input to identify and filter out).

If the use of information (letters, digits) sandwiched between useless information (non-letters, numbers, punctuation), but also to identify and filter out. Sensitive words mz, then enter the m &#　z also filtered, but the input m1 is, and z is not filtered.



To filter L4 and Fd and D26 of these three words, and the length of the input string is 20 characters.