#include<bits/stdc++.h>
using namespace std;
#define IOS ios::sync_with_stdio(0);cin.tie(0);cout.tie(0)
typedef long long ll;
const double pi=acos(-1.0); //圆周率，精确到了15位。圆周率：3.14159265358979323846
const double eps=1e-8;   //偏差值。
int sgn(double x)
{
	if(fabs(x)<eps) return 0;  //x==0,返回0。
	else return x<0?-1:1;     //x<0返回-1,x>0返回1。
}
int dcmp(double x,double y)
{
	if(fabs(x-y)<eps) return 0;
	else return x<y?-1:1;
}
struct Point{
	ll x,y;
	int id;
	Point(){}
	Point(ll x,ll y):x(x),y(y){}
	Point operator + (Point B) {return Point(x+B.x,y+B.y);}
	Point operator - (Point B) {return Point(x-B.x,y-B.y);}
	Point operator * (double k) {return Point(x*k,y*k);}
	Point operator / (double k) {return Point(x/k,y/k);}
	bool operator == (Point B) {return sgn(x-B.x)==0&&sgn(y-B.y)==0;}
	bool operator < (Point B){
		return (sgn(x-B.x)<0)||(sgn(x-B.x)==0&&sgn(y-B.y)<0);
	}
};
//两点间距离
double Dist(Point A,Point B) { return sqrt((A.x-B.x)*(A.x-B.x)+(A.y-B.y)*(A.y-B.y));}

typedef Point Vector;

//点积，>0锐角,<0钝角,=0直角
double Dot(Vector A,Vector B){ return A.x*B.x+A.y*B.y; }

//求向量A的长度
//有小数
double Len1(Vector A){return sqrt(Dot(A,A));}
//不开方，用于比较长度
double Lne2(Vector A){return Dot(A,A);}

//求向量A和向量B的夹角
double Angle(Vector A,Vector B){return acos(Dot(A,B)/Len1(A)/Len1(B));}

//叉积 >0在A的逆时针方向，<0在A的顺时针方向，=0共线(可能同向或反向)
ll Cross(Vector A,Vector B){return A.x*B.y-A.y*B.x;}

//已知一条直线两点a,b,求点c到直线的距离
double dist_line(Point a,Point b,Point c)
{
    Point v1=b-a,v2=c-b;
    return fabs(Cross(v1,v2)/Len1(v1));
}

ll S(Point a,Point b,Point c)
{
	return abs(Cross(a-b,a-c));
}

int Convex_hull(Point *p,int n,Point *ch)
{
	//n=unique(p,p+n)-p;//对点去重
	sort(p,p+n);  //对点排序：
	int v=0;
	//求下凸包，如果p[i]是右拐弯的，这个点不在凸包上，退回
	for(int i=0;i<n;i++)
	{
		while(v>1&&sgn(Cross(ch[v-1]-ch[v-2],p[i]-ch[v-1]))<=0)
			v--;
		ch[v++]=p[i];
	}
	int j=v;
	//求上凸包
	for(int i=n-2;i>=0;i--)
	{
		while(v>j&&sgn(Cross(ch[v-1]-ch[v-2],p[i]-ch[v-1]))<=0)
			v--;
		ch[v++]=p[i];
	}
	if(n>1)    //返回值v是凸包的顶点数
		v--;
	return v;
}
const int N=1e5+10;
Point p[N],ch[N],p1[N],ch1[N];
int main()
{
	IOS;
	int T;
	cin>>T;
	while(T--)
	{
		ll n;
		cin>>n;
		for(int i=0;i<n;i++)
		{
			cin>>p[i].x>>p[i].y;
			p[i].id=i;
		}
		vector<ll>vis(n+10);
		int t=Convex_hull(p,n,ch);
		if(t==n)
		{
			cout<<"-1\n";
		}
		else
		{
			ll sum=0;
			for(int i=0;i<t;i++)
			{
				long double t1;
				vis[ch[i].id]=1;
				t1=Cross(ch[i],ch[(i+1)%n]);
				sum+=t1;
			}
			sum=abs(sum);
			ll m=0;
			for(int i=0;i<n;i++)
			{
				if(vis[p[i].id]==0)
				{
					p1[m]=p[i];
					m++;
				}
			}
			if(m<3)
			{
				ll max1=0;
				for(int i=0;i<m;i++)
				{
					for(int j=0;j<t;j++)
					{
						ll t1=S(p1[i],ch[j],ch[(j+1)%t]);
						if(t1)
							max1=max(max1,sum-t1);
					}
				}
				cout<<(ll)max1<<"\n";
			}
			else
			{
				int t1=Convex_hull(p1,m,ch1);
				ll min1;
				ll l=0;
				for(int i=0;i<t1;i++)
				{
					if(S(ch1[i],ch[0],ch[1])<S(ch1[l],ch[0],ch[1]))
						l=i;
				}
				min1=S(ch1[l],ch[0],ch[1]);
				for(int i=0;i<t;i++)
				{
					ll x=(i+1)%t;
					while(S(ch1[(l+1)%t1],ch[i],ch[x])<S(ch1[l],ch[i],ch[x]))
						l=(l+1)%t1;
					while(S(ch1[(l-1+t1)%t1],ch[i],ch[x])<S(ch1[l],ch[i],ch[x]))
						l=(l-1+t1)%t1;
					min1=min(min1,S(ch1[l],ch[i],ch[x]));
				}
				cout<<(ll)(sum-min1)<<"\n";
			}
		}
	}
	return 0;
}