#include<bits/stdc++.h>
#define L(i, l, r) for(int i = l; i <= r; i ++)
#define R(i, l, r) for(int i = l; i >= r; i --)
#define fi first
#define se second
#define ll long long
#define ld long double
#define vi vector <int>
#define vl vector <long long>
#define endl '\n' 
#define sz(a) ((int) (a).size())
#define me(f, x) memset(f, x, sizeof(f))
#define ull unsigned long long
using namespace std;
const double eps = 1e-8;
const double pi  = 3.141592653589793284l;

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(fabs(x - a.x) <= eps){
            return y < a.y;
        }
        return x < a.x;
    }
    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 T k)  const{
        return {x * k, y * k};
    }
    point operator / (const T k)  const{
        return {x / k, y / k};
    }
    point operator - () const{
        return {- x, - y};
    }
    T operator * (const point &a) const{ // Dot
        return x * a.x + y * a.y;
    }   
    T operator ^ (const point &a) const{ // Cross
        return x * a.y - y * a.x;
    }
    int to_left(const point &a) const{
        const auto t = (*this) ^ a;
        return (t > eps) - (t < -eps); // 1: this 在 a left  // 0：this 与 a 共线 // -1 this 在a right
    }
    int area() const {
        if (y > 0 || y == 0 && x > 0)
            return 0;
        return 1;
    }
    // 极角排序2 : bool operator <(const Point& rhs) const { return area() < rhs.area() || area() == rhs.area() && cross(rhs) > 0; }
    T   length2() const{
        return (*this) * (*this);
    }
    T   dist2(const point &a) const{
        return (a - (*this)).length2();
    }
    double length() const{
        return sqrt(length2());
    }
    double dist(const point &a) const{
        return (a - (*this)).length();
    }
    friend auto &operator<<(ostream &os, point p) {
        return os << "(" << p.x << ", " << p.y << ")";
    }
}; 
// 这里看情况换double || long long || long double
using Point = point<ll>;
typedef Point Vector;
typedef vector<Point> Polygon;

bool argcmp(const Point &a, const Point &b){
    // 下半 < 原点 < +x轴 < 上半 < -x轴
    auto quad =[](const Point &a){
        if(a.y < -eps) return 1;  // 下半平面，三四象限。
        if(a.y >  eps) return 4;  // 上半平面，一二象限。
        if(a.x < -eps) return 5;  // -x轴
        if(a.x >  eps) return 3;  // +x轴
        return 2;                 // 原点
    };
    int qa = quad(a), qb = quad(b);
    if(qa != qb) return qa < qb;
    auto t = a ^ b;
    if(t == 0) return a * a < b * b - eps; // 如果共线，则近的在前面。
    return t > eps;   // 同一半平面内to_left测试, 大于0表示a在b的左边，排前面。
}

int sgn(double x){
    if(fabs(x) <= eps) return 0;
    return x > 0 ? 1 : -1;
}
// 两点距离
double dis(Point a, Point b){
    return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));
}
//叉积
ll cross(Vector v1, Vector v2){
    return v1.x * v2.y - v1.y * v2.x;
}
// to_left测试
int to_left(Point &a, Point &o, Point &b){
    int t = (a - o) ^ (b - o);
    if(sgn(t) == 0) return 0;
    return t > 0 ? 1 : -1;
}
// 求凸包
Polygon Andrew(vector<Point> s){
    vector<Point> a, b;
    if(s.size() <= 2) return s;
    sort(s.begin(), s.end());
    int sz = s.size();
    a.push_back(s[0]), a.push_back(s[1]);
    b.push_back(s[sz - 1]), b.push_back(s[sz - 2]);

    for(int i = 2; i < sz; i ++){
        for(int j = a.size(); j >= 2; j --){
            Vector v1 = a[j - 1] - a[j - 2], v2 = s[i] - a[j - 1];
            if( (v1 ^ v2) >= 0) a.pop_back();
            else break;
        }
        a.push_back(s[i]);
    }
    for(int i = sz - 3; i >= 0; i --){
        for(int j = b.size(); j >= 2; j --){
            Vector v1 = b[j - 1] - b[j - 2], v2 = s[i] - b[j - 1];
            if( (v1 ^ v2) >= 0) b.pop_back();
            else break;
        } 
        b.push_back(s[i]);
    }
    reverse(b.begin(), b.end());
    int len = a.size();
    for(int i = len - 2; i >= 1; i --) b.push_back(a[i]);
    return b;
}
void solve(){
    int n; cin >> n;
    vector <Point> vec;

    for(int i = 1; i <= n; i ++){
        ll x, y; cin >> x >> y;
        vec.push_back({x,  y});
    }

    Polygon out = Andrew(vec);

    ll ans = 0;
    for(int i = 0; i < sz(out); i ++){
        ans += cross(out[i], out[(i + 1) % sz(out)]);
    }

    map <pair<ll, ll>, int> mp;
    for(auto [x, y] : out){
        mp[{x, y}] = 1;
    }

    vector <Point> A;
    for(auto [x, y] : vec){
        if(!mp[{x, y}]) A.push_back({x, y});
    }
    if(A.empty()){
        cout << -1 << endl;
        return ;
    }

    // {
    //     // bf
    //     ll mn = 5e18;
    //     ll m  = sz(in);
    //     out.push_back(out[0]);

    //     for(int i = 0; i < m; i ++){
    //         for(int j = 0; j + 1 < out.size(); j ++){
    //             assert(cross(out[j] - in[i], out[j + 1] - in[i]) >= 0);
    //             mn = min(mn, cross(out[j] - in[i], out[j + 1] - in[i]));
    //         }
    //     }
    //     cout << ans - mn << endl;
    // }

    Polygon in = Andrew(A);
    int pos = -1; ll mn = 5e18;
    int m = sz(in);
    for(int i = 0; i < sz(in); i ++){
        ll area = cross(out[0] - in[i], out[1] - in[i]);
        assert(area >= 0);
        if(area < mn){
            pos = i;
            mn  = min(mn, area);
        }
    }

    // {
    //     for(auto &p : out){
    //         cout << p << endl;
    //     }
    // }

    int siz = out.size();
    for(int i = 1; i < sz(out); i ++){
        Point x = out[i], y = out[(i + 1) % siz];
        mn = min(mn, cross(x - in[pos], y - in[pos]));
        while(cross(x - in[pos], y - in[pos]) > cross(x - in[(pos + 1) % m], y - in[(pos + 1) % m])){
            assert(cross(x - in[pos], y - in[pos]) >= 0);
            assert(cross(x - in[(pos + 1) % m], y - in[(pos + 1) % m]) >= 0);
            mn  = min(mn, cross(x - in[(pos + 1) % m], y - in[(pos + 1) % m]));
            pos = (pos + 1) % m;
        }
    }
    cout << ans - mn << endl;
}
signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    
    int Case; cin >> Case; while(Case --) solve();

    return 0;
}