问题 AJ: Dropping tests

In a certain course, you take n tests. If you get a_i out of b_i questions correct on test i, your cumulative average is defined to be
.
Given your test scores and a positive integer k, determine how high you can make your cumulative average if you are allowed to drop any k of your test scores.
Suppose you take 3 tests with scores of 5/5, 0/1, and 2/6. Without dropping any tests, your cumulative average is . However, if you drop the third test, your cumulative average becomes .

The input test file will contain multiple test cases, each containing exactly three lines. The first line contains two integers, 1≤n≤1000 and $.$ The second line contains n integers indicating ai for all i. The third line contains n positive integers indicating bi for all i. It is guaranteed that 0≤ai≤bi≤1,000,000,000. The end-of-file is marked by a test case with n = k = 0 and should not be processed.

For each test case, write a single line with the highest cumulative average possible after dropping k of the given test scores. The average should be rounded to the nearest integer.

3 1
5 0 2
5 1 6
4 2
1 2 7 9
5 6 7 9
0 0

83
100

To avoid ambiguities due to rounding errors, the judge tests have been constructed so that all answers are at least 0.001 away from a decision boundary (i.e., you can assume that the average is never 83.4997).