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

#define F first
#define S second
#define all(x) x.begin(), x.end()
#define sz(x) (int)x.size()

const int N = 2e5 + 200;

struct pt {
    long long x, y;
    pt(long long x = 0, long long y = 0) : x(x), y(y) {}

    pt operator-(const pt &p) { return pt(x - p.x, y - p.y); }
    long long operator*(const pt &p) { return x * p.y - y * p.x; }

} p[N];

bool operator<(const pt &a, const pt &b) {
    if (a.x == b.x) return a.y < b.y;
    return a.x < b.x;
}

int n;
int del[N];

vector<int> hull() {

    vector<int> lower;
    for (int i = 1; i <= n; ++i) {
        if (del[i]) continue;
        while (sz(lower) > 1 && (p[lower.end()[-1]] - p[lower.end()[-2]]) * (p[i] - p[lower.end()[-2]]) < 0)
            lower.pop_back();
        lower.push_back(i);
    }
    vector<int> upper;
    for (int i = n; i >= 1; --i) {
        if (del[i]) continue;
        while (sz(upper) > 1 && (p[upper.end()[-1]] - p[upper.end()[-2]]) * (p[i] - p[upper.end()[-2]]) < 0)
            upper.pop_back();
        upper.push_back(i);
    }
    lower.pop_back();
    upper.pop_back();
    lower.insert(lower.end(), upper.begin(), upper.end());
    return lower;
}

void solve() {
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        del[i] = 0;
        cin >> p[i].x >> p[i].y;
    }
    sort(p + 1, p + n + 1);
    vector<int> oh = hull();
    if (sz(oh) == n) {
        cout << -1 << '\n';
        return;
    }
    long long total = 0;
    for (int i = 0; i < sz(oh); ++i) {
        total += p[oh[i]] * p[oh[(i + 1) % sz(oh)]];
    }
    // cerr << total << '\n';
    for (int i : oh) {
        del[i] = 1;
    }
    if (n - sz(oh) <= 2) {
        long long ans = 0;
        for (int i = 0; i < sz(oh); ++i) {
            // cerr << "POINT:\n";
            // cerr << p[oh[i]].x << " " << p[oh[i]].y << '\n';
            for (int j = 1; j <= n; ++j) {
                if (del[j] == 0) {
                    // cerr << (p[oh[(i + 1) % sz(oh)]] - p[oh[i]]) * (p[j] - p[oh[i]]) << '\n';
                    ans = max(ans, total - (p[oh[(i + 1) % sz(oh)]] - p[oh[i]]) * (p[j] - p[oh[i]]));
                }
            }
        }
        cout << ans << '\n';
        return;
    }
    auto ok = [](pt a, pt b, pt c) {
      return (b * a > 0 && a * c >= 0);  
    };
    vector<int> ih = hull();
    long long ans = 0;
    // for (int i : ih)
    //     cerr << p[i].x << " " << p[i].y << '\n';
    for (int i = 0, j = 0; i < sz(oh); ++i) {
        pt v = p[oh[(i + 1) % sz(oh)]] - p[oh[i]];
        // cerr << v.x << " " << v.y << '\n';
        while (!ok(v, p[ih[(j+1)%sz(ih)]] - p[ih[j]],  p[ih[(j+2)%sz(ih)]] - p[ih[(j+1)%sz(ih)]])) {
            j = (j+1)%sz(ih);
        }
        ans = max(ans, total - (v * (p[ih[(j+1)%sz(ih)]] - p[oh[i]])));
    }
    cout << ans << '\n';
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    int T = 1;
    cin >> T;
    while (T--) solve();
}