Description
Given N numbers. You need to separate them A and B such that is 
minimum.
Input
Each case starts with a positive integer N (1 <= N <= 20), then the next line contains exactly N integers (range from -100000 to 100000).
A test case of N = 0 indicates the end of input, and should not be processed.
Output
Output one line per case that contains an integer denoting the minimum value of .