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

#define endl '\n'
#define int long long

struct P {
    int x, y, id;
    bool operator < (const P &b) const {
        return x != b.x ? x < b.x : y < b.y;
    }
};

int cross(P x, P y) {
    return x.x * y.y - x.y * y.x;
}

P operator - (P x, P y) {
    P c{};
    c.x = x.x - y.x;
    c.y = x.y - y.y;
    return c;
}

int calc(P x, P y, P z) {
    P xy = y - x;
    P xz = z - x;
    return abs(cross(xy, xz));
}

bool check(P p, P q, P r) {
    return cross(q - p, r - q) < 0;
}

vector<P> chull(vector<P> ps) {
    sort(ps.begin(), ps.end());
    vector<int> I{0}, used(ps.size());
    for (int i = 1; i < ps.size(); i++) {
        while (I.size() > 1 && !check(ps[I[I.size() - 2]], ps[I.back()], ps[i]))
            used[I.back()] = 0, I.pop_back();
        used[i] = 1, I.push_back(i);
    }
    for (int i = ps.size() - 2; i >= 0; i--) {
        if (used[i])
            continue;
        while (I.size() > 1 && !check(ps[I[I.size() - 2]], ps[I.back()], ps[i]))
            I.pop_back();
        I.push_back(i);
    }
    vector<P> H;
    for (int i = 0; i < I.size() - 1; i++)
        H.push_back(ps[I[i]]);
    return H;
}

int area(vector<P> &ps) {
    int sum = 0;
    for(int i = 0;i < ps.size();i++) {
        int nxt = (i + 1) % (int)ps.size();
        sum += cross(ps[i], ps[nxt]);
    }
    return abs(sum);
}

void solve() {
    int n; cin >> n;
    vector<P> pt(n);
    for(int i = 0;i < n;i++) cin >> pt[i].x >> pt[i].y, pt[i].id = i;
    vector<int> vis(n);
    auto out = chull(pt);
    auto get = [&] (P tmp) {
        int mn = 5e18;
        for(int i = 0;i < out.size();i++) {
            int nxt = (i + 1) % (int)out.size();
            mn = min(mn, calc(tmp, out[i], out[nxt]));
        }
        return mn;
    };
    for(auto [x, y, id] : out) vis[id] = 1;
    vector<P> ptin;
    int ans = area(out);
    for(int i = 0;i < n;i++) if(!vis[i]) ptin.push_back(pt[i]);
    if(ptin.size() < 3) {
        if(ptin.empty()) {
            cout << -1 << endl;
        }
        else {
            int mn = 5e18;
            for(auto it : ptin) {
                mn = min(mn, get(it));
            }
            cout << ans - mn << endl;
        }
        return;
    }
    auto in = chull(ptin);
    int i = 0, j = 0, mn = 5e18;
    int osiz = (int)out.size(), isiz = (int)in.size();
    for(int jj = 0;jj < in.size();jj++) {
        int tmp = calc(out[0], out[1], in[jj]);
        if(tmp < mn) {
            mn = tmp;
            j = jj;
        }
    }
    for(i = 1;i < out.size();i++) {
        while(calc(in[(j + 1) % isiz], out[i], out[(i + 1) % osiz]) < calc(in[j], out[i], out[(i + 1) % osiz])) j = (j + 1) % isiz;
        mn = min(mn, calc(in[j], out[i], out[(i + 1) % osiz]));
    }
    cout << ans - mn << endl;
}
//sto SpadeZ orz
signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int T = 1;
    cin >> T;
    while(T--) {
        solve();
    }
    return 0;
}