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

using ll = long long;

void solve() {
    int N;
    cin >> N;

    vector<ll> A(N);
    for (int i = 0; i < N; i++) {
        cin >> A[i];
    }

    vector<ll> plus, minus;
    for (ll a: A) {
        if (a >= 0) plus.push_back(a);
        if (a <= 0) minus.push_back(a);
    }

    if (plus.size() == 0 || minus.size() == 0) {
        ll min_a = *min_element(A.begin(), A.end());
        ll max_a = *max_element(A.begin(), A.end());

        cout << min_a * max_a << "\n";
    } else {
        ll min_plus = *min_element(plus.begin(), plus.end());
        ll max_minus = *max_element(minus.begin(), minus.end());

        cout << min_plus * max_minus << "\n";
    }
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int T;
    cin >> T;

    while (T--) solve();
}