//#include "testlib.h"
//#include <spoj.h>
 
#include <iostream>
#include <stdio.h>
#include <vector>
#include <string>
#include <algorithm>
#include <math.h>
#include <cmath>
#include <assert.h>
#include <time.h>
#include <memory.h>
#include <set>
#include <numeric>
#include <map>
#include <queue>
#include <stack>
#include <bitset>
 
using namespace std;
 
typedef pair<long long, long long> point;
 
bool cw(const point &a, const point &b, const point &c) {
    return (b.first - a.first) * (c.second - a.second) - (b.second - a.second) * (c.first - a.first) < 0;
}
 
vector<point> convexHull(vector<point> p) {
    int n = (int)p.size();
    if (n <= 1)
        return p;
    int k = 0;
    sort(p.begin(), p.end());
    vector<point> q(n * 2);
    for (int i = 0; i < n; q[k++] = p[i++])
        for (; k >= 2 && !cw(q[k - 2], q[k - 1], p[i]); --k)
            ;
    for (int i = n - 2, t = k; i >= 0; q[k++] = p[i--])
        for (; k > t && !cw(q[k - 2], q[k - 1], p[i]); --k)
            ;
    q.resize(k - 1 - (q[0] == q[1]));
    return q;
}
 
long long triangle_area(point p1, point p2, point p3) {
    return (p2.first - p1.first)*(p3.second - p1.second) - (p2.second - p1.second)*(p3.first - p1.first);
}
 
int main() {
    ios::sync_with_stdio(0);
    int t;
    cin >> t;
    while (t --> 0) {
        int n;
        cin >> n;
        vector<point> all(n);
        set<point> s;
        for(int i = 0; i < n; ++i) {
            cin >> all[i].first >> all[i].second;
            s.insert(all[i]);
        }
        
        vector<point> c1 = convexHull(all);
        for(auto x : c1)
            s.erase(x);
        
        vector<point> c2;
        for(auto x : s)
            c2.push_back(x);
        
        c2 = convexHull(c2);
        
        if (c2.size() == 0)
            cout << "-1\n";
        else {
            long long area = 0;
            for(int i = 1; i+1 < c1.size(); ++i)
                area += abs(triangle_area(c1[0], c1[i], c1[i+1]));
            
            long long mn = 1e18;
            int p = 0;
            for(int i = 0; i < c1.size(); ++i) {
                long long curr = abs(triangle_area(c1[i], c1[(i+1) % c1.size()], c2[p]));
                long long nx, start = p;
                while (true) {
                    nx = abs(triangle_area(c1[i], c1[(i+1) % c1.size()], c2[(p+1) % c2.size()]));
                    if (nx <= curr) {
                        curr = nx;
                        p = (p+1) % c2.size();
                    }
                    else {
                        //p = (p-1+c2.size())%c2.size();
                        break;
                    }
                    if (start == p)
                        break;
                }
                mn = min(mn, curr);
            }
            cout << area - mn << "\n";
        }
    }
    
    return 0;
}