1 #include<iostream>
2 #include<stdio.h>
3 #include<set>
4 #define MAXN 305
5 using namespace std;
6 int a[MAXN];
7 int mod[MAXN];
8 set<int> coll;
9 set<int>::iterator pos;
10 int main()
11 {
12 ///freopen("acm.acm","r",stdin);
13 int test;
14 int g;
15 int i;
16 bool boo;
17 int j;
18 int k;
19 int modo;
20 scanf("%d",&test);
21 while(test --)
22 {
23 scanf("%d",&g);
24 for(i = 0; i < g; ++ i)
25 {
26 scanf("%d",&a[i]);
27 }
28 for(j = g ;; ++ j)
29 {
30 boo = false;
31 for(i = 0; i < g; ++ i)
32 {
33 mod[i] = a[i]%j;
34 }
35 for(i = 0; i < g; ++ i)
36 {
37 for(k = i + 1; k < g; ++ k)
38 {
39 if(mod[i] == mod[k])
40 //boo = true;
41 break;
42 }
43 if(k < g)
44 break;
45 }
46 if(i == g)
47 {
48 printf("%d\n",j);
49 break;
50 }
51 }
52 }
53 }
