Description
Given N numbers. You need to separate them A and B such that 
is minimum.
Note that a set can be empty.
Input
Each case starts with a positive integer N, then the next line contains exactly N integers n1~nN.
A test case of N = 0 indicates the end of input, and should not be processed.
For case 1, 1<=N<=3, 0<=ni<=100
For case 2, 1<=N<=5, 0<=ni<=10000
For case 3, 1<=N<=10, 0<=ni<=100000
For case 4, 1<=N<=20, -1000000<=ni<=1000000
Hint: Try to enumerate all possible combinitions.
Output
Output one line per case that contains an integer denoting the minimum value of .