#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for (int i = a; i < b; i++)
using ll = long long;

int main(){
	int t;
	cin >> t;
	rep(ti, 0, t) {
		int n;
		cin >> n;
		vector<ll> a(n);
		rep(i, 0, n) cin >> a[i];
		int p = 0, m = 0, z = 0;
		ll pma = 0, pmi = 2e9, mma = -2e9, mmi = 0;
		rep(i, 0, n) {
			if(a[i] == 0) z++;
			else if(a[i] < 0) {
				m++;
				mma = max(mma, a[i]);
				mmi = min(mmi, a[i]);
			}
			else {
				p++;
				pma = max(pma, a[i]);
				pmi = min(pmi, a[i]);
			}
		}
		ll ans = 0;
		if(z == 0) {
			if(m == 0) ans = pma * pmi;
			else if(p == 0) ans = mma * mmi;
			else ans = pmi * mma;
		}
		cout << ans << endl;
	}
}