#include<queue>
#include<math.h>
#include<stdio.h>
#include<iostream>
#include<vector>
#include<iomanip>
#include<algorithm>
#include<cstdio> 
#include<utility>
#include<cstring>
#include<stack>
#include<fstream>
#include<string>
using namespace std;
#define LL long long
const int N = 1e5 + 10;
const int INF = 0x3f3f3f3f;
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 )
{
	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;
}