#include<bits/stdc++.h>
#define endl '\n'
#define int long long
using namespace std;
int n;
struct VECTOR
{
	double x,y;
	double operator^(const VECTOR &v)const
	{
		return x*v.y-y*v.x;
	}
};
struct POINT
{
	double x,y;
	bool operator<(const POINT &p)const
	{
		if(x==p.x)return y<p.y;
		else return x<p.x;
	}
	bool operator==(const POINT &p)const
	{
		return x==p.x&&y==p.y;
	}
	VECTOR operator-(const POINT &p)const
	{
		return {x-p.x,y-p.y};
	}
}p[100005];
int cross(VECTOR v1,VECTOR v2)
{
	return v1^v2;
}
vector<POINT> st;
int sub;
POINT p0;
bool check(POINT p)
{
	POINT back1=st.back(),back2=*(st.rbegin()+1);
	if(cross(back1-back2,p-back1)<=0)
	{
		if(cross(p-back1,back1-back2)<sub)
		{
			sub=cross(p-back1,back1-back2);
			p0=back1;
		}
		return 1;
	}
	return 0;
}
void andrew()
{
	st.clear();
	sort(p+1,p+n+1);
	for(int i=1;i<=n;i++)
	{
		while(st.size()>1&&check(p[i]))st.pop_back();
		st.push_back(p[i]);
	}
	int k=st.size();
	for(int i=n-1;i>=1;i--)
	{
		while(st.size()>k&&check(p[i]))st.pop_back();
		st.push_back(p[i]);
	}
	st.pop_back();
}
void solve()
{
	cin>>n;
	for(int i=1;i<=n;i++)
		cin>>p[i].x>>p[i].y;
	sub=1e18;
	p0={1e9+1,1e9+1};
	andrew();
	int area=0;
	for(int i=0;i<st.size();i++)
	{
		POINT o={0,0};
		VECTOR v=st[i]-o,v1=st[(i+1)%n]-o;
		area+=cross(v,v1);
		if(st[i]==p0)
		{
			cout<<-1<<endl;
			return;
		}
	}
	cout<<area-sub<<endl;;
}
signed main()
{
	ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
	int T=1;
	cin>>T;
	while(T--)solve();
	return 0;
}
/*
2
6
-2 0
1 -2
5 2
0 4
1 2
3 1
4
0 0
1 0
0 1
1 1
*/