2017 Fall Waterloo Local ACM Contest, Problem C
Vera has integers . A margin is a non-negative integer such that it is possible to choose integers such that for all , , the interval contains at least of Vera's integers and also contains .
Compute the minimum possible margin.
Input
Line contains integers and .
Line contains integers, .
Output
Print one line with one integer, the minimum possible margin.
Sample Input
5 3
1 -2 10 5 4
Sample Output
6
Note
For the first example, one possible solution is to choose , which is illustrated below.
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