#include<bits/stdc++.h>
using namespace std;
int t,n,a;
int sumz,sumf,sum0;
long long zup[6],zdown[6],fup[6],fdown[6];
long long maxn;
void init(){
	sumz=0;
	sumf=0;
	sum0=0;
	memset(zup,20005,sizeof(zup));
	memset(zdown,-20005,sizeof(zdown));
	memset(fup,20005,sizeof(fup));
	memset(fdown,-20005,sizeof(fdown));
	maxn=-20005;
	return;
}
bool cmp_up(int a,int b){//i 
	return a<b;
}
bool cmp_down(int a,int b){
	return a>b;
}
int main(){
	cin>>t;
	for(int s=1;s<=t;s++){
		cin>>n;
		init();
		for(int i=1;i<=n;i++){
			cin>>a;
			if(a>0){
				sumz++;
				zup[5]=a;
				zdown[5]=a;
				sort(zup+1,zup+6,cmp_up);
				sort(zdown+1,zdown+6,cmp_down);
			}else if(a==0)sum0++;
			else if(a<0){
				sumf++;
				fup[5]=a;
				fdown[5]=a;
				sort(fup+1,fup+6,cmp_up);
				sort(fdown+1,fdown+6,cmp_down);
			}
		}
		if(sum0>0)maxn=max(maxn,(long long)0);
		if(sumz>=4)maxn=max(maxn,zdown[1]*zdown[2]*zdown[3]*zdown[4]);
		if(sumz>=3&&sumf>=1)maxn=max(maxn,zup[1]*zup[2]*zup[3]*fdown[1]);
		if(sumz>=2&&sumf>=2)maxn=max(maxn,zdown[1]*zdown[2]*fup[1]*fup[2]);
		if(sumz>=1&&sumf>=3)maxn=max(maxn,zup[1]*fdown[1]*fdown[2]*fdown[3]);
		if(sumf>=4)maxn=max(maxn,fup[1]*fup[2]*fup[3]*fup[4]);
		cout<<maxn<<endl;
	}
	return 0;
}