#ifdef local
#pragma GCC optimize(1)
#pragma GCC optimize(2)
#pragma GCC optimize(3)
#endif
// #pragma comment(linker, "/STACK:102400000,102400000")

#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <chrono>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>

#ifndef local
#define endl '\n'
#endif

#define pb emplace_back
#define fi first
#define se second
#define rep(i, l, r) for (long long i = l; i <= r; i++)
#define IOS ios::sync_with_stdio(0), cin.tie(0), cout.tie(0)
#define mem(a, x) memset(a, x, sizeof(a))
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef double db;
typedef pair<ll, ll> P;
typedef pair<P, ll> PP;
const double pi = acos(-1);
typedef __int128_t int128;
const db eps = 1e-9;
std::mt19937_64 rng(time(0));
ll my_random(ll l, ll r)
{

	uniform_int_distribution<int> range(l, r);
	return range(rng);
}
void __()
{
#ifdef local
	system("pause");
#endif
}
ll qp(ll a, ll b, ll mod)
{
	ll ans = 1;
	while (b)
	{
		if (b & 1)
			ans = ans * a % mod;
		a = a * a % mod;
		b >>= 1;
	}
	return ans;
}

const int maxn = 1e5 + 10;

int n;

struct Point
{
	ll x, y;
	Point() {}
	Point(db _x, db _y) : x(_x), y(_y) {}
	Point operator+(const Point &t) const
	{
		return Point(x + t.x, y + t.y);
	}
	Point operator-(const Point &t) const
	{
		return Point(x - t.x, y - t.y);
	}
	ll operator*(const Point &t) const
	{
		// 叉积
		return x * t.y - y * t.x;
	}
	ll operator^(const Point &t) const
	{
		// 点积
		return x * t.x + y * t.y;
	}
	bool operator==(const Point &t) const
	{
		return (x - t.x) == 0 && (y - t.y) == 0;
	}
	bool operator!=(const Point &t) const
	{
		return !((*this) == t);
	}
	db len() const
	{
		return sqrt(x * x + y * y);
	}
};

Point p[maxn], p2[maxn];
set<P> st;
Point c1[maxn], c2[maxn];
Point areap[10];

struct Line
{
	Point s, e;
	Line() {}
	Line(Point _s, Point _e) : s(_s), e(_e) {}
	db disToSegment(const Point &t) const
	{
		return {abs(1.0 * ((t - s) * (e - s)) / (e - s).len())};
	}
};

ll area(Point p[], int n)
{
	ll sum = 0;
	p[n + 1] = p[1];
	for (int i = 1; i <= n; i++)
		sum += p[i + 1] * p[i];
	p[n + 1] = Point();
	return abs(sum);
}

void convex_hull(Point p[], Point c[], int n, int &num)
{
	// O(nlogn),c为凸包,起始点只包含一次
	// 凸包存在c中, 凸包大小为num
	num = 0;
	auto cmp = [](Point &p, Point &q)
	{
		return p.x == q.x ? (p.y < q.y) : (p.x < q.x);
	};
	sort(p + 1, p + n + 1, cmp);
	c[1] = p[1];
	num = 1;
	for (int i = 2; i <= n; i++)
	{
		while (num > 1 && ((c[num] - p[i]) * (c[num] - c[num - 1])) <= 0)
			num--;
		num++, c[num] = p[i];
	}
	int tmp = num;
	for (int i = n - 1; i >= 1; i--)
	{
		while (num > tmp && ((c[num] - p[i]) * (c[num] - c[num - 1])) <= 0)
			num--;
		num++, c[num] = p[i];
	}
	if (num > 1)
		c[num] = Point(0, 0), num--;
}

int main()
{
	IOS;
	int _;
	cin >> _;
	for (int _1 = 1; _1 <= _; _1++)
	{
		st.clear();
		cin >> n;
		for (int i = 1; i <= n + 5; i++)
			c1[i] = c2[i] = p[i] = p2[i] = Point();
		for (int i = 1; i <= n; i++)
		{
			cin >> p[i].x >> p[i].y;
			st.insert(P{p[i].x, p[i].y});
		}
		int num1 = 0;
		convex_hull(p, c1, n, num1);
		ll ans = area(c1, num1);
		// cout << num1 << " " << ans << endl;
		for (int i = 1; i <= num1; i++)
			st.erase(P{c1[i].x, c1[i].y});
		// for (int i = 1; i <= num1; i++)
		//{
		//	cout << c1[i].x << " " << c1[i].y << endl;
		// }
		// cout << "YYY" << endl;
		if (st.size() == 0)
		{
			cout << -1 << endl;
			continue;
		}
		int cnt = 0;
		for (auto x : st)
		{
			p2[++cnt] = Point(x.fi, x.se);
		}

		int num2 = 0;
		convex_hull(p2, c2, cnt, num2);
		// cout << "XXX " << num2 << endl;
		// for (int i = 1; i <= num2; i++)
		//{
		//	cout << c2[i].x << " " << c2[i].y << endl;
		// }
		// cout << "YYY" << endl;
		int flag = 1;
		Line l = Line(c1[1], c1[2]);
		for (int i = 1; i <= num2; i++)
			if (l.disToSegment(c2[i]) < l.disToSegment(c2[flag]))
				flag = i;
		areap[1] = c1[1], areap[2] = c1[2], areap[3] = c2[flag];
		// cout << "XXX " << flag << " " << c1[1].x << " " << c1[1].y << " " << c1[2].x << " " << c1[2].y << " " << c2[flag].x << " " << c2[flag].y << endl;
		ll bns = area(areap, 3);
		for (int i = 2; i <= num1; i++)
		{
			Line l = Line(c1[i], c1[(i == num1 ? 1 : i + 1)]);
			// cout << i << " " << (i == num1 ? 1 : i + 1) << endl;
			while (l.disToSegment(c2[flag]) - l.disToSegment(c2[flag == num2 ? 1 : flag + 1]) > 1e-9)
			{
				// cout << "XX " << flag<<" "<<num2 <<" "<<l.disToSegment(c2[flag == num2 ? 1 : num2 + 1]) <<" "<<l.disToSegment(c2[flag]) << endl;
				flag++;
				if (flag == num2 + 1)
					flag = 1;
			}
			areap[1] = c1[i], areap[2] = c1[(i == num1 ? 1 : i + 1)], areap[3] = c2[flag];
			// cout << "XXX " << flag << " " << c1[i].x << " " << c1[i].y << " " << c1[(i == num1 ? 1 : i + 1)].x << " " << c1[(i == n ? 1 : i + 1)].y << " " << c2[flag].x << " " << c2[flag].y << endl;
			bns = min(bns, area(areap, 3));
			// cout << "X  " << bns << endl;
		}
		// cout << ans << " " << bns << endl;
		cout << ans - bns << endl;
	}
	__();
	return 0;
}
/*
1
8
0 0
4 0
0 4
4 4
1 2
2 1
2 3
3 2
*/