#include<iostream>
#include<queue>
#include<stack>
#include<math.h>
#include<string.h>
#include<algorithm>
using namespace std;
const int maxn=1e5+10;
int number[maxn];
int main(){
	int n;
	scanf("%d", &n);
	while(n--){
		int m;
		scanf("%d", &m);
		for(int i=0;i<m;i++){
			scanf("%d", &number[i]);
		}
		int ans=0,k;
		while(m>1){
			sort(number+ans,number+m);
			for(int i=ans;i<m;i++){
				if(number[i]==0){
					ans++;
				}else{
					break;
				}
			}
			if(ans>0){
				ans--;
			}
			k=ans;
			for(int i=k;i<m-1;i++){
				number[i]=number[i+1]-number[i];
			}
			m--;
		}
		printf("%d\n", number[ans]);
	}
}