#include<bits/stdc++.h>
#define double long double
using namespace std;
#define debugging 0
const int maxn = 100010;
const double eps = 1e-9;
bool lt(double a, double b) {
//	return a < b;
    return a - b < -eps;
}


struct Point {
    double x, y;
    Point() {}
    Point(double _x, double _y) {x = _x, y = _y;};
    Point operator - (const Point &b) const {
        return Point(x - b.x, y - b.y);
    }
    bool operator < (const Point &b) const {
        if (x != b.x)
            return x < b.x;
        return y < b.y;
    }
} a[maxn];

double cross(Point a, Point b) {
    return a.x * b.y - a.y * b.x;
}

bool check(Point a, Point b, Point c) {
    return lt(0, cross(b - a, c - a));
}

double cal(Point a, Point b, Point c) {
    double res = b.x * c.y + a.x * b.y + a.y * c.x - 
	             a.y * b.x - b.y * c.x - a.x * c.y;
	return abs(res);
}

vector<Point> chull(vector<Point> &vp) {
    sort(vp.begin(), vp.end());
    vector<int> ve{0}, vis(vp.size());
    #define CHECK (check(vp[ve[ve.size() - 2]], vp[ve.back()], vp[i]))
    for (int i = 1; i < vp.size(); ++i) {
        while (ve.size() > 1 && !CHECK) {
		    vis[ve.back()] = 0;
			ve.pop_back();
		}    
        vis[i] = 1;
		ve.push_back(i);
    }
    for (int i = vp.size() - 2; i >= 0; --i) {
        if (vis[i])  continue;
        while (ve.size() > 1 && !CHECK) {
		    ve.pop_back(); 	
		}
        ve.push_back(i);
    }
    vector<Point> res;
    for (int i = 0; i < ve.size() - 1; ++i) {
    	res.push_back(vp[ve[i]]);
	}
    return res;
}

vector<Point> three_size(vector<Point> vp) {
	int sz = vp.size();
	for (int num = 0; num < 2; ++num) {
		for (int i = 0; i < sz; ++i) {
			vp.push_back(vp[i]);
		}
	}
	return vp;
}

int n; 
double ans, mn;
set<Point> st; 

void solve() {

    scanf("%d", &n);
    vector<Point> v1, v2;
    for (int i = 1; i <= n; ++i) {
//    	scanf("%lf%lf", &a[i].x, &a[i].y);
    	scanf("%Lf %Lf", &a[i].x, &a[i].y);
    	v1.push_back(a[i]);
	}
    v1 = chull(v1);
	ans = 0;
	for (int i = 1; i < v1.size() - 1; ++i) {
		ans += cal(v1[0], v1[i], v1[i+1]);
	}
	
	st.clear();
    for (Point i: v1) {
    	st.insert(i);
	}
    for (int i = 1; i <= n; ++i) {
    	if (st.find(a[i]) == st.end()) {
    		v2.push_back(a[i]);
		}
	}
    
    if (v2.empty()) {
        printf("-1\n");
        return;
    }

    if (v2.size() > 2) {
    	v2 = chull(v2);
	}
	
//	three_size(v1);
//	three_size(v2);
	v1 = three_size(v1);
	v2 = three_size(v2);
    
    int u = 0; // ...
    mn = 3e18;

	for (int i = 0; i < v1.size() - 1; ++i) {
		Point a = v1[i], b = v1[i+1];
		while (u < v2.size() - 1 && cal(a, b, v2[u]) > cal(a, b, v2[u+1])) {
			u++;
		}
		mn = min(mn, cal(a, b, v2[u]));
	}
//    printf("%.0lf\n", ans - mn);
    printf("%.0Lf\n",ans-mn);
} 

int main() {
    int tt = 1;
//    IOS
//    cin >> tt;
    scanf("%d", &tt);
    while (tt--) {
        solve();
    }
    
    return 0;
}
/*


*/