You are given N distinct Numbers: A_1 to A_N. Find the smallest number M such that the new sequence A_i % M is also unique.
Input:
First line contains integer T denoting the number of test cases.
For each test case next line is the length of the sequence N followed by the sequence in next line.
Output:
For each test case print answer in separate lines.
constraints:
1<=N<=500
0<=A_i<=1000000