304412: CF844A. Diversity
Memory Limit:256 MB
Time Limit:1 S
Judge Style:Text Compare
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Submit:0
Solved:0
Description
Diversity
题意翻译
给出一个字符串$S$与一个整数$k$。 你可以更改$S$中的任意字符,使得字符串$S$中有不小于$k$个不同的字符。 求最少的更改次数。 $1\le k \le 26, 1\le |S|\le 1000.$题目描述
Calculate the minimum number of characters you need to change in the string $ s $ , so that it contains at least $ k $ different letters, or print that it is impossible. String $ s $ consists only of lowercase Latin letters, and it is allowed to change characters only to lowercase Latin letters too.输入输出格式
输入格式
First line of input contains string $ s $ , consisting only of lowercase Latin letters ( $ 1<=|s|<=1000 $ , $ |s| $ denotes the length of $ s $ ). Second line of input contains integer $ k $ ( $ 1<=k<=26 $ ).
输出格式
Print single line with a minimum number of necessary changes, or the word «impossible» (without quotes) if it is impossible.
输入输出样例
输入样例 #1
yandex
6
输出样例 #1
0
输入样例 #2
yahoo
5
输出样例 #2
1
输入样例 #3
google
7
输出样例 #3
impossible