STAMPS - Stamps

# 题目描述 大家都讨厌Raymond。他是地球上最大的邮票收藏家，正因为如此，他总是在集邮聚会上取笑其他人。幸运的是，每个人都爱露西，她有自己的计划。她私下问她的朋友们是否可以借给她一些邮票，这样她就可以通过展示比Raymond更大的藏品来让Raymond难堪。Raymond对自己的优越性很有把握，所以他总是说他要展示多少邮票。露西知道她拥有多少邮票，所以她知道她还需要多少邮票。她也知道有多少朋友会借给她一些邮票。但她喜欢向尽可能少的朋友借邮票，如果她需要向太多的朋友借邮票，那么她宁愿根本不去与Raymond比。你能告诉她需要向多少朋友借邮票吗？ # 输入输出格式 ## 输入格式 第一行包含方案的数量。每个场景都描述了一个收藏家聚会，它的第一行告诉你露西需要借多少邮票(1 ~ 1000000)，还有多少朋友(1 ~ 1000)提供给她一些邮票。在第二行，你将得到邮票的数量(1 ~ 10000)，她的每个朋友提供的身份证(?)。 ## 输出格式 每个场景的输出以包含**"Scenario #i:"**的一行开始，其中我是从1开始的场景数。然后用最少的朋友数量打印一行，露西需要向他们借邮票。如果这是不可能的，即使她从每个人那里借来了一切，那就写"**impossible** "。**用空行终止方案的输出**

Everybody hates Raymond. He’s the largest stamp collector on planet earth and because of that he always makes fun of all the others at the stamp collector parties. Fortunately everybody loves Lucy, and she has a plan. She secretly asks her friends whether they could lend her some stamps, so that she can embarrass Raymond by showing an even larger collection than his. Raymond is so sure about his superiority that he always tells how many stamps he’ll show.And since Lucy knows how many she owns, she knows how many more she needs. She also knows how many friends would lend her some stamps and how many each would lend. But she’s like to borrow from as few friends as possible and if she needs too many then she’d rather not do it at all. Can you tell her the minimum number of friends she needs to borrow from?

The first line contains the number of scenarios. Each scenario describes one collectors party and its first line tells you how many stamps (from 1 to 1000000) Lucy needs to borrow and how many friends (from 1 to 1000) offer her some stamps. In a second line you’ll get the number of stamps (from 1 to 10000) each of her friends id offering.

The output for every scenario begins with a line containing “Scenario #i:”, where i is the number of the scenario starting at 1. Then print a single line with the minimum number of friends Lucy needs to borrow stamps from. If it’s impossible even if she borrows everything from everybody, write impossible. Terminate the output for the scenario with a blank line.

3
100 6
13 17 42 9 23 57
99 6
13 17 42 9 23 57
1000 3
314 159 265

Scenario #1:
3

Scenario #2:
2

Scenario #3:
impossible