#include<bits/stdc++.h>

#define x first
#define y second

using namespace std;

using vec = std::pair<int64_t, int64_t>;

vec operator+(const vec& a, const vec& b) {
	return {a.x + b.x, a.y + b.y};
}

vec operator-(const vec& a, const vec& b) {
	return {a.x - b.x, a.y - b.y};
}

int64_t dot_prod(const vec& a, const vec& b) {
	return 1ll * a.x * b.x + 1ll * a.y * b.y;
}

int64_t cross_prod(const vec& a, const vec& b) {
	return 1ll * a.x * b.y - 1ll * a.y * b.x;
}

vector<vec> convex_hull(vector<vec> points) {
    vec p0 = points[0];
    for (vec p : points) {
        if (p.x < p0.x || (p.x == p0.x && p.y < p0.y)) {
            p0 = p;
        }
    }
    for (vec &x : points) {
        x.x -= p0.x;
        x.y -= p0.y;
    }
    sort(points.begin(), points.end(), [&](const vec& a, const vec& b){
        return cross_prod(a, b) > 0 || (cross_prod(a, b) == 0 && a.x * a.x + a.y * a.y < b.x * b.x + b.y * b.y);
    });
    vector<vec> hull;
    for (vec p : points) {
        while (hull.size() >= 2 && (cross_prod(p - hull.back(), hull[hull.size() - 2] - hull.back()) <= 0)) {
            hull.pop_back();
        }
        hull.push_back(p);
    }
    for (vec &x : hull) {
        x.x += p0.x;
        x.y += p0.y;
    }
    return hull;
}

void solve() {
	int n;
	cin >> n;
	vector<vec> a(n);
	for (int i = 0; i < n; i++) {
		cin >> a[i].x >> a[i].y;
	}
	int64_t ans = 0;
	vector<vec> hull1 = convex_hull(a);
	for (int i = 0; i < hull1.size(); i++) {
		int j = i + 1;
		if (j == hull1.size()) {
			j = 0;
		}
		ans += cross_prod(hull1[i], hull1[j]);
	}
	set<vec> st(a.begin(), a.end());
	for (auto i : hull1) {
		st.erase(i);
	}
	if (st.size() == 0) {
		cout << "-1\n";
		return;
	}
	vector<vec> hull2;
	if (st.size() < 3) {
		hull2 = vector<vec>(st.begin(), st.end());
	} else {
		hull2 = convex_hull(vector<vec>(st.begin(), st.end()));
	}
	// cout << ans << '\n';
	// cout << "hull1\n"; 
	// for (auto i : hull1) {
	// 	cout << i.x << ' ' << i.y << '\n';
	// }
	// cout << "hull2\n"; 
	// for (auto i : hull2) {
	// 	cout << i.x << ' ' << i.y << '\n';
	// }
	int64_t mn = 8e18;
	for (int i = 0; i < hull1.size(); ++i) {
		auto a = hull1[i];
		auto b = hull1[i == hull1.size() - 1 ? 0 : i + 1];
		auto get = [&](vec c) {
			return std::abs(cross_prod(a - b, c - b));
		};
		int pos = 0;
		for (int k = 20; k >= 0; --k) {
			int l = pos - (1 << k), r = pos + (1 << k);
			for (int j = l; j <= r; j += 1 << k) {
				if (j < 0) j = -(-j % hull2.size());
				int id = (j + hull2.size()) % hull2.size();
				// std::cout << i << ' ' << k << ' ' << j << ' ' << id << ' ' << hull2.size() << std::endl;
				if (get(hull2[id]) < get(hull2[pos])) pos = id;
			}
			// std::cout << i << ' ' << k << ' ' << pos << std::endl;
		}
		mn = std::min(mn, get(hull2[pos]));
	}
	std::cout << ans - mn << '\n';
}

int32_t main() {
	cin.tie(nullptr)->sync_with_stdio(false);
	int t = 1;
	cin >> t;
	while (t--) {
		solve();
	}
}