#include<bits/stdc++.h>
using namespace std;
#define timelimitexceeded ios_base::sync_with_stdio(false),cin.tie(NULL),cout.tie(0);
#define endl "\n" 
using namespace std;
typedef long long ll;
typedef pair<int, int> PII; 
typedef pair<long long, long long> PLL;
const int N = 1e5 + 10,INF = 0x3f3f3f3f;
const ll MOD = 998244353, LLINF = 1e18, MOD2 = 1e9 + 7;
 
ll read()
{
	ll x = 0, f = 1;
	char ch = getchar();
	while(ch < '0' || ch > '9') {if(ch == '-') f = -1; ch = getchar();}
	while(ch >= '0' && ch <= '9'){x = x * 10 + (ch - '0'); ch = getchar();}
	return x * f;
}
ll qmi(ll x, ll y, ll mod)
{
	ll res = 1;
	while(y)
	{
		if(y & 1) res *= x;	res %= mod; 
		x *= x;	x %= mod; y >>= 1;
	}
	return res;
}
ll exgcd(ll a, ll b, ll &x, ll &y)
{
	if(b == 0)
	{
		x = 1,  y = 0;
		return a;
	}
	ll ret = exgcd(b, a % b, y, x);
	y -= a / b * x;
	return ret;
}
ll getInv(ll a, ll mod)
{
	ll x, y;
	ll d = exgcd(a, mod, x, y);
	return (x % mod + mod) % mod;
}
ll low_bit(ll x){return (x & (-1 * x));}

void write(ll x)
{
	if(x == 0){putchar('0');return;}
	ll len = 0, k1 = x, c[100010];
	if(k1 < 0) k1 = -1 * k1, putchar('-');
	while(k1) c[len++] = k1 % 10 + '0', k1 /= 10;
	while(len--) putchar(c[len]);
}

struct point{
	long double x, y;
	point(){}
	point(long double _x, long double _y){x = _x, y = _y;}
	point operator - (const point &A) const{
	return point(x - A.x, y - A.y);}
	bool operator < (const point &A) const{
		if(x != A.x) return x < A.x;
		return y < A.y;
	}
}a[N];
//叉积 
long double cross(point a, point b)
{
	return a.x * b.y - a.y * b.x;
}
//点积 
long double dot(point a, point b)
{
	return a.x * b.x + a.y * b.y;
}
//多边形面积 
long double area(vector<point> points)
{
	int n_points = points.size();
	long double res = 0.0;
	for(int i = 0; i < n_points; i++)
	{
		res += cross(points[i], points[(i + 1) % n_points]);
	}
	return abs(res);	
}
//求凸包 
auto cHull(vector<point> a) {
    sort(a.begin(), a.end(), [&](auto a, auto b) {
        if (a.x != b.x) {
            return a.x < b.x;
        } else {
            return a.y < b.y;
        }
    });
    vector<point> l, h;
    for (auto p : a) {
        while (l.size() > 1 && cross(l.back() - l[l.size() - 2], p - l.back()) <= 0) 
{
            l.pop_back();
        }
        while (h.size() > 1 && cross(h.back() - h[h.size() - 2], p - h.back()) >= 0) 
{
            h.pop_back();
        }
        l.push_back(p);
        h.push_back(p);
    }
    reverse(h.begin(), h.end());
    h.insert(h.end(), l.begin() + 1, l.end() - 1);
    return h;
 }
void three_size(vector<point> &now)
{
	int sz = now.size();

	for(int i = 0 ; i < 2; i ++)
	{
		for(int j = 0; j < sz; j++)
			now.push_back(now[j]);
	}
	
}

void solve() 
{
	long double ans = 0;
	int n;
	cin >>n;
	vector<point> v1, v2;
	for(int i = 1; i <= n; i++)
	{
		scanf("%Lf%Lf", &a[i].x, &a[i].y);
		v1.push_back(a[i]);
	}
	v1 = cHull(v1);
	for(int i = 1; i < v1.size() - 1;i++)
	{
		ans += area({v1[0], v1[i], v1[i + 1]});
	}
//	ans = area(v1);
	set<point> st;
	for(auto a: v1) st.insert(a);
	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);
	long double minn = 3e18;
	for(int i = 0, j = 0; i < v1.size() - 1; i++)
	{
		point a = v1[i], b = v1[i + 1];
		while(j < v2.size() - 1 && area({a, b, v2[j]}) > area({a, b, v2[j + 1]}))
		{
			j++;
		}
		minn = min(minn, area({a, b, v2[j]}));
	}
//	printf("%.0Lf %Lf\n", ans, minn);
	printf("%.0Lf\n", ans - minn);
}

int main(void)
{
	
	//timelimitexceeded
	int _;
	cin >> _;
//	_ = 1;
	while(_--)
	{

		solve();
	}
    return 0;
 }