// (◕ᴗ◕✿)

// #pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define srep(i, s, n) for (ll i = s; i < (n); i++)
#define len(x) ((int)(x).size())
#define all(x) (x).begin(), (x).end()
using namespace std;
template<typename T> using vc = vector<T>;
template<typename T> using vv = vc<vc<T>>;
template<typename T> using vvv = vv<vc<T>>;
using vi = vc<int>;using vvi = vv<int>; using vvvi = vv<vi>;
using ll = long long;using vl = vc<ll>;using vvl = vv<ll>; using vvvl = vv<vl>;
using ld = long double; using vld = vc<ld>; using vvld = vc<vld>; using vvvld = vc<vvld>;
using uint = unsigned int;
using ull = unsigned long long;
const ld pi = acos(-1.0);
const int inf = 0x3f3f3f3f;
const ll INF = 0x3f3f3f3f3f3f3f3f;
// const ll mod = 1000000007;
const ll mod = 998244353;
inline bool inside(ll y, ll x, ll H, ll W) {return 0 <= (y) and (y) < (H) and 0 <= (x) and (x) < (W); }

#define debug(var) do { cerr << #var << " :\n"; view(var); } while(0)
template<typename T>void view(const T& e) {cerr << e;}
template<typename T1, typename T2>void view(const pair<T1, T2>& p) {cerr << "{" << p.first << ", " << p.second << "}";}
template<typename T>void view(const vc<T>& v) {for (const auto& e : v) {view(e);cerr << " ";} cerr << endl;}
template<typename T>void view(const vv<T>& vv) {for (const auto& v : vv) {view(v);} cerr << endl;}
template<typename T>void view(const set<T>& s) {for (const auto& e : s) {view(e);cerr << " ";} cerr << endl;}
template<typename T>void view(const multiset<T>& s) {for (const auto& e : s) {view(e);cerr << " ";} cerr << endl;}
template<typename T>void view(const unordered_set<T>& s) {for (const auto& e : s) {view(e);cerr << " ";} cerr << endl;}
template<typename T1, typename T2>void view(const map<T1, T2>& mp){for (const auto& e : mp) {view(e);cerr << " ";} cerr << endl;}

void solve(){
    int N; cin >> N;
    vl A(N); rep(i, N) cin >> A[i];
    vl plus, minus;
    int zero = 0;
    for (auto a : A){
        if (a > 0) plus.push_back(a);
        else if (a < 0) minus.push_back(a);
        else zero++;
    }
    if (zero) cout << 0 << endl;
    else if (len(plus) && len(minus)){
        sort(all(plus));
        sort(all(minus));
        cout << plus[0] * minus.back() << endl;
    }else{
        if (len(minus)) swap(plus, minus);
        sort(all(plus));
        cout << plus[0] * plus.back() << endl;
    }
}
int main(){
    int T; cin >> T;
    while (T--) solve();
}