#include <bits/stdc++.h>
using namespace std;
#define rep(i, d, u) for(int i = d; i <= u; ++i)
#define cep(n) while(n--)
const int _maxn = 100011;
struct node {
	int xa, ya;
} nods[_maxn];
long long calc(node le, node ri, node mi) {
	return 1ll * (le . xa - mi . xa) * (ri . ya - mi . ya) - 1ll * (ri . xa - mi . xa) * (le . ya - mi . ya);
}
long long mabs(long long da) {
	return da < 0 ? -da : da;
}
void dmin(long long &le, long long ri) {
	if(le > ri) {
		le = ri;
	}
}
int t, n, latp, ratp, poin;
bool pdif[_maxn];
long long rans, dans;
vector<int> uatp, datp;
vector<node> usta, dsta, idot, udox, ddox;
int main() {
	cin >> t;
	cep(t) {
		cin >> n, rans = 0;
		rep(i, 1, n) {
			cin >> nods[i] . xa >> nods[i] . ya, pdif[i] = 0;
		}
		sort(nods + 1, nods + n + 1, [](node le, node ri) {
			return le . xa == ri . xa ? le . ya < ri . ya : le . xa < ri . xa;
		});
		if(nods[1] . xa == nods[n] . xa) {
			puts("-1");
			continue;
		}
		for(latp = 1; nods[1] . xa == nods[latp + 1] . xa && latp + 1 <= n; ) {
			++latp;
		}
		for(ratp = n; nods[n] . xa == nods[ratp - 1] . xa && ratp - 1 >= 1; ) {
			--ratp;
		}
		usta . clear(), uatp . clear();
		rep(i, 1, n) {
			while(usta . size() >= 2 && calc(usta . back(), nods[i], usta[usta . size() - 2]) < 0) {
				usta . pop_back(), uatp . pop_back();
			}
			usta . push_back(nods[i]), uatp . push_back(i);
		}
		dsta . clear(), datp . clear();
		rep(i, 1, n) {
			while(dsta . size() >= 2 && calc(dsta . back(), nods[i], dsta[dsta . size() - 2]) > 0) {
				dsta . pop_back(), datp . pop_back();
			}
			dsta . push_back(nods[i]), datp . push_back(i);
		}

		for(int i : uatp) {
			pdif[i] = 1;
		}
		for(int i : datp) {
			pdif[i] = 1;
		}
		idot . clear();
		rep(i, latp + 1, ratp - 1) {
			if(!pdif[i]) {
				idot . push_back(nods[i]);
			}
		}
		if(idot . empty()) {
			puts("-1");
			continue;
		}
		sort(idot . begin(), idot . end(), [](node le, node ri) {
			return le . xa == ri . xa ? le . ya < ri . ya : le . xa < ri . xa;
		}), udox . clear(), ddox . clear();
		for(node i : idot) {
			while(udox . size() >= 2 && calc(udox . back(), i, udox[udox . size() - 2]) < 0) {
				udox . pop_back();
			}
			udox . push_back(i);
		}
		for(node i : idot) {
			while(ddox . size() >= 2 && calc(ddox . back(), i, ddox[ddox . size() - 2]) > 0) {
				ddox . pop_back();
			}
			ddox . push_back(i);
		}
		poin = 0;
		rep(i, 0, usta . size() - 2) {
			rans += mabs(calc(usta[i], usta[i + 1], nods[1]));
		}
		rep(i, 0, dsta . size() - 2) {
			rans += mabs(calc(dsta[i], dsta[i + 1], nods[1]));
		}
		dans = rans, poin = 0;
		rep(i, 0, usta . size() - 2) {
			while(poin + 1 < udox . size() &&
			mabs(calc(udox[poin], usta[i], usta[i + 1])) > mabs(calc(udox[poin + 1], usta[i], usta[i + 1]))) {
				++poin;
			}
			dmin(dans, mabs(calc(udox[poin], usta[i], usta[i + 1])));
		}
		poin = 0;
		rep(i, 0, dsta . size() - 2) {
			while(poin + 1 < ddox . size() &&
			mabs(calc(ddox[poin], dsta[i], dsta[i + 1])) > mabs(calc(ddox[poin + 1], dsta[i], dsta[i + 1]))) {
				++poin;
			}
			dmin(dans, mabs(calc(ddox[poin], dsta[i], dsta[i + 1])));
		}
		cout << rans - dans << endl;
	}
	return 0;
}