#include <bits/stdc++.h>
using namespace std;
using LL = long long;
using point_t = long long;
//using point_t = long double;  //全局数据类型

constexpr point_t eps = 1e-8;
constexpr point_t INF = numeric_limits<point_t>::max();
constexpr long double PI = 3.1415926535897932384l;

// 点与向量
template<typename T>
struct point {
    T x, y;

    bool operator==(const point& a) const { return (abs(x - a.x) <= eps && abs(y - a.y) <= eps); }
    bool operator<(const point& a) const { if (abs(x - a.x) <= eps) return y < a.y - eps; return x < a.x - eps; }
    bool operator>(const point& a) const { return !(*this < a || *this == a); }
    point operator+(const point& a) const { return { x + a.x,y + a.y }; }
    point operator-(const point& a) const { return { x - a.x,y - a.y }; }
    point operator-() const { return { -x,-y }; }
    point operator*(const T k) const { return { k * x,k * y }; }
    point operator/(const T k) const { return { x / k,y / k }; }
    T operator*(const point& a) const { return x * a.x + y * a.y; }  // 点积
    T operator^(const point& a) const { return x * a.y - y * a.x; }  // 叉积，注意优先级
    int toleft(const point& a) const { const auto t = (*this) ^ a; return (t > eps) - (t < -eps); }  // to-left 测试
    T len2() const { return (*this) * (*this); }  // 向量长度的平方
    T dis2(const point& a) const { return (a - (*this)).len2(); }  // 两点距离的平方

    // 涉及浮点数
    long double len() const { return sqrtl(len2()); }  // 向量长度
    long double dis(const point& a) const { return sqrtl(dis2(a)); }  // 两点距离
    long double ang(const point& a) const { return acosl(max(-1.0l, min(1.0l, ((*this) * a) / (len() * a.len())))); }  // 向量夹角
    point rot(const long double rad) const { return { x * cos(rad) - y * sin(rad),x * sin(rad) + y * cos(rad) }; }  // 逆时针旋转（给定角度）
    point rot(const long double cosr, const long double sinr) const { return { x * cosr - y * sinr,x * sinr + y * cosr }; }  // 逆时针旋转（给定角度的正弦与余弦）
};

using Point = point<point_t>;

LL cross(Point a, Point b, Point c) { //叉积  
    return (b.x - a.x) * (c.y - a.y) - (b.y - a.y) * (c.x - a.x);
}

int t = 0;
vector<int>convex(vector<Point>& p) {
    sort(p.begin() + 1, p.end());
    int n = p.size() - 1;
    if (n == 1) {
        t = 1;
        return { 0,1 };
    }
    if (n == 2) {
        t = 2;
        return { 0,1,2 };
    }
    vector<int>s(n + 10);
    t = 0;
    for (int i = 1;i <= n;i++) {
        while (t > 1 and cross(p[s[t - 1]], p[s[t]], p[i]) <= 0) {
            t--;
        }
        s[++t] = i;
    }
    int k = t;
    for (int i = n - 1;i >= 1;i--) {
        while (t > k and cross(p[s[t - 1]], p[s[t]], p[i]) <= 0) {
            t--;
        }
        s[++t] = i;
    }
    t--;
    return s;
}

void solve() {

    int n;
    cin >> n;
    vector<Point>a(n + 1);
    for (int i = 1;i <= n;i++) {
        cin >> a[i].x >> a[i].y;
    }
    vector<Point>b, wd, nd;
    b.push_back({ 0,0 });
    auto s = convex(a);

    if (t == n || n <= 3) {
        cout << "-1\n";return;
    }

    vector<int>vis(n + 1);
    for (int i = 1;i <= t;i++) {
        vis[s[i]] = 1;
        wd.push_back(a[s[i]]);
    }

    for (int i = 1;i <= n;i++) {
        if (!vis[i])b.push_back(a[i]);
    }

    s = convex(b);

    for (int i = 1;i <= t;i++) {
        nd.push_back(b[s[i]]);
    }

    LL sum = 0, ans = INF;


    int wn = wd.size(), nn = nd.size();

    for (int i = 1;i < wn - 1;i++) {
        sum += (wd[i] - wd[0]) ^ (wd[i + 1] - wd[0]);
    }

    auto nxtj = [&](int x, int t = 1) {
        return (x + t) % nn;
    };
    auto nxti = [&](int x, int t = 1) {
        return (x + t) % wn;
    };

    // for (auto [x, y] : wd) {
    //     cout << x << " " << y << "\n";
    // }
    // cout << "\n";
    // for (auto [x, y] : nd) {
    //     cout << x << " " << y << "\n";
    // }
    for (int i = 0, j = 0;i < wn;i++) {
        for (;;) {
            LL cur = cross(wd[i], wd[nxti(i)], nd[j]);
            LL ne = cross(wd[i], wd[(nxti(i))], nd[nxtj(j)]);
            ans = min({ ans,cur,ne });
            if (ne >= cur)break;
            j = nxtj(j);
        }
    }
    // auto [x, y] = wd[3];
    // cout << x << " " << y << "\n";
    // cout << sum << "\n";
    // for (int i = 0, j = 0;i < wn;i++) {
    //     while (cross(nd[j], wd[i], wd[nxti(i)]) >= cross(nd[nxtj(j)], wd[i], wd[nxti(i)]))j = nxtj(j);
    //     // cerr << i << " " << nxti(i) << "\n";
    //     // cerr << i << " " << j << "\n\n";
    //     // cerr << cross(nd[j], wd[i], wd[nxti(i)]) << "\n";
    //     // cerr << cross(nd[nxtj(j)], wd[i], wd[nxti(i)]) << "\n\n";
    //     // cerr << wd[i] << " " << wd[nxti(i)] << "\n";
    //     // auto [x, y] = wd[i];
    //     // auto [xz, zy] = wd[nxti(i)];
    //     // auto [xx, yy] = nd[j];
    //     ans = max(ans, sum - cross(nd[j], wd[i], wd[nxti(i)]));
    // }

    cout << sum - ans << "\n";
    // for (int i = 1;i <= t;i++) {
    //     nd.push_back(b[s[i]]);
    // }

    // for (auto [x, y] : wd) {
    //     cout << x << " " << y << "\n";
    // }
    // cout << "\n";
    // for (auto [x, y] : nd) {
    //     cout << x << " " << y << "\n";
    // }
}

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    int T = 1;
#ifdef LOCAL
    freopen("data.in", "r", stdin);
    freopen("data.out", "w", stdout);
#endif
    cin >> T;
    while (T--)
        solve();
    return 0;
}