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

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

    int T;
    cin >> T;
    while (T--) {
        int N;
        cin >> N;

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

        bool hasZero = false;
        bool hasPos = false, hasNeg = false;

        long long minA = LLONG_MAX, maxA = LLONG_MIN;
        long long minPos = LLONG_MAX;   // smallest positive
        long long maxNeg = LLONG_MIN;   // largest negative (closest to 0)

        for (long long x : A) {
            if (x == 0) hasZero = true;
            if (x > 0) {
                hasPos = true;
                minPos = min(minPos, x);
            }
            if (x < 0) {
                hasNeg = true;
                maxNeg = max(maxNeg, x);
            }
            minA = min(minA, x);
            maxA = max(maxA, x);
        }

        long long ans;
        if (hasZero) {
            ans = 0;
        } else if (!hasPos || !hasNeg) {
            // all same sign
            ans = minA * maxA;
        } else {
            ans = minPos * maxNeg;
        }

        cout << ans << '\n';
    }
    return 0;
}