有一种加密方法为：其使用一个字母串（可以含重复字母，字母个数不超过50）作为密钥。假定密钥单词串为feather，则先去掉密钥单词中的重复字母得到单词串feathr，然后再将字母表中的其它字母以反序追加到feathr的后面-There is an encryption method: its use a string of letters (which can contain repeated letters, the number of not more than 50 letters) as the key. Assume that the key word string as feather, first remove the key word is repeated in the letters to get the word string feathr, and then the other letters in the alphabet in reverse order appended to the back of feathr