#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
#define ov4(a, b, c, d, name, ...) name
#define rep3(i, a, b, c) for (ll i = (a); i < (b); i += (c))
#define rep2(i, a, b) rep3(i, a, b, 1)
#define rep1(i, n) rep2(i, 0, n)
#define rep0(n) rep1(aaaaa, n)
#define rep(...) ov4(__VA_ARGS__, rep3, rep2, rep1, rep0)(__VA_ARGS__)
const ll INF = LLONG_MAX / 4;
template <class T>
using vc = vector<T>;
template <class T>
using vvc = vc<vector<T>>;
template <class T>
struct Point {
    using P = Point;
    T x, y;
    explicit Point(T x = 0, T y = 0) : x(x), y(y) {}
    bool operator<(P p) const { return tie(x, y) < tie(p.x, p.y); }
    bool operator==(P p) const { return tie(x, y) == tie(p.x, p.y); }
    P operator-(P p) const { return P(x - p.x, y - p.y); }
    T cross(P p) const { return x * p.y - y * p.x; }
    T cross(P a, P b) const { return (a - *this).cross(b - *this); }
};
using P = Point<ll>;
vc<P> ch(vc<P> pts) {
    if (pts.size() <= 1) return pts;
    sort(pts.begin(), pts.end());
    vc<P> h(pts.size() + 1);
    ll s = 0, t = 0;
    for (int it = 0; it < 2; ++it, s = --t, reverse(pts.begin(), pts.end())) {
        for (P p : pts) {
            while (t >= s + 2 and h[t - 2].cross(h[t - 1], p) <= 0) t--;
            h[t++] = p;
        }
    }
    return {h.begin(), h.begin() + t - (t == 2 && h[0] == h[1])};
}
void solve() {
    ll n;
    cin >> n;
    vc<P> pos;
    map<P, ll> cnt;
    rep(i, n) {
        ll x, y;
        cin >> x >> y;
        pos.push_back(P(x, y));
        cnt[P(x, y)]++;
    }
    auto v = ch(pos);
    ll sz = v.size();
    if (sz <= 2) {
        cout << 0 << endl;
        return;
    }
    ll res = 0;
    auto calc = [&](P p1, P p2, P p3) {
        p2 = p2 - p1, p3 = p3 - p1;
        return abs(p2.x * p3.y - p2.y * p3.x);
    };
    if (sz == 3) {
        ll base = calc(v[0], v[1], v[2]);
        ll res = 0;
        rep(i, n) {
            if (pos[i] == v[0] or pos[i] == v[1] or pos[i] == v[2]) {
                if (cnt[pos[i]] == 1) continue;
                res = base;
            } else {
                rep(j, 3) {
                    ll area = base - calc(v[j], v[(j + 1) % 3], pos[i]);
                    res = max(res, area);
                }
            }
        }
        if (res % 2)
            cout << res / 2 << ".5" << endl;
        else
            cout << res / 2 << endl;
        return;
    }
    rep(a, sz) {
        ll b = a, d = a;
        for (ll c = a + 2; c < a + sz - 1; c++) {
            while (b <= a) b++;
            while (d <= c) d++;
            while (b + 1 < c and calc(v[a], v[c % sz], v[(b + 1) % sz]) > calc(v[a], v[c % sz], v[b % sz])) b++;
            while (d + 1 < a + sz - 1 and calc(v[a], v[c % sz], v[(d + 1) % sz]) > calc(v[a], v[c % sz], v[d % sz]))
                d++;
            res = max(res, calc(v[a], v[c % sz], v[b % sz]) + calc(v[a], v[c % sz], v[d % sz]));
        }
    }
    if (res % 2)
        cout << res / 2 << ".5" << endl;
    else
        cout << res / 2 << endl;
}
int main() {
    cin.tie(0)->sync_with_stdio(0);
    cout << fixed << setprecision(20);
    ll t = 1;
    cin >> t;
    for (int i = 1; i <= t; i++) solve();
}