#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <queue>
#include <map>
#include <set>
#include <cassert>
using namespace std;
using ll=long long;
const int maxn=2e5+5;
#define double long double
const double eps=1e-12;
const ll mod=998244353;
const int maxp=1e5+5;
int sgn(double x) {
    if(fabs(x)<eps)
        return 0;
    if(x<0) return -1;
    return 1;
}
double sqr(double x) {
    return x*x;
}
struct Point{
    double x,y;
    Point(){}
    Point(double _x,double _y) {
        x=_x;
        y=_y;
    }
    bool operator == (const Point& b) const {
        return sgn(x-b.x)==0&&sgn(y-b.y)==0;
    }
    bool operator < (const Point& b) const {
        return sgn(x-b.x)==0?sgn(y-b.y)<0:x<b.x;
    }
    Point operator - (const Point& b) const {
        return Point(x-b.x,y-b.y);
    }
    Point operator + (const Point& b) const {
        return Point(x+b.x,y+b.y);
    }
    double operator ^ (const Point& b) const {
        return x*b.y-y*b.x;
    }
    double operator * (const Point& b) const {
        return x*b.x+y*b.y;
    }
    double distance(Point b) {
        return hypot(x-b.x, y-b.y);
    }
};
struct Polygon {
    int n;
    Point p[maxp];
    struct cmp {
        Point p;
        cmp(const Point& p0) {
            p=p0;
        }
        bool operator() (const Point& aa,const Point& bb) {
            Point a=aa,b=bb;
            int d=sgn((a-p)^(b-p));
            if(d==0)
                return sgn(a.distance(p)-b.distance(p))<0;
            return d>0;
        }
    };
    void norm() {
        Point mi=p[0];
        for(int i=1;i<n;i++) mi=min(mi,p[i]);
        sort(p,p+n,cmp(mi));
    }
    void getconvex(Polygon& convex) {
        sort(p,p+n);
        convex.n=n;
        for(int i=0;i<min(n,2);i++) {
            convex.p[i]=p[i];
        }
        if(convex.n==2&&convex.p[0]==convex.p[1])
            convex.n--;
        if(n<=2) return;
        int &top=convex.n;
        top=1;
        for(int i=2;i<n;i++) {
            while (top&&sgn((convex.p[top]-p[i])^(convex.p[top-1]-p[i]))<=0) {
                top--;
            }
            convex.p[++top]=p[i];
        }
        int tmp=top;
        convex.p[++top]=p[n-2];
        for(int i=n-3;i>=0;i--) {
            while (top!=tmp&&sgn((convex.p[top]-p[i])^(convex.p[top-1]-p[i]))<=0) {
                top--;
            }
            convex.p[++top]=p[i];
        }
        if(convex.n==2&&convex.p[0]==convex.p[1])
            convex.n--;
        convex.norm();
    }
    double getarea() {
        double sum=0;
        for(int i=0;i<n;i++)
            sum+=p[i]^p[(i+1)%n];
        return fabs(sum)/2;
    }
};
double area(Point p,Point s,Point e) {
    return fabs(((p-s)^(p-e))/2);
}
void solve() {
    int n;
    cin>>n;
    Polygon poly,c;
    poly.n=n;
    for(int i=0;i<n;i++) {
        int x,y;
        cin>>x>>y;
        poly.p[i]=Point(x, y);
    }
    poly.getconvex(c);
    map<Point,int> mp;
    for(int i=0;i<c.n;i++)
        mp[c.p[i]];
    Polygon tmp,c2;
    int cnt=0;
    for(int i=0;i<poly.n;i++) {
        if(!mp.count(poly.p[i]))
            tmp.p[cnt++]=poly.p[i];
    }
    if(cnt==0) {
        cout<<"-1\n";
        return;
    }
    tmp.n=cnt;
    tmp.getconvex(c2);
    if(c2.n<=2){
        double ans=9e18;
        for(int i=0;i<c.n;i++) {
            Point s=c.p[i],e=c.p[(i+1)%c.n];
            ans=min(ans,area(c2.p[0], s, e));
            ans=min(ans,area(c2.p[c2.n-1], s, e));
        }
        assert(sgn(ans)>0);
        cout<<(ll)((c.getarea()-ans)*2+eps)<<"\n";
        return;
    }
    int p=0;
    double mn=9e18;
    for(int i=0;i<c2.n;i++) {
        double d=area(c2.p[i], c.p[0], c.p[1]);
        if(d<mn) {
            mn=d;
            p=i;
        }
    }
    double ans=9e18;
    for(int i=0;i<c.n;i++) {
        Point s=c.p[i],e=c.p[(i+1)%c.n];
        while (c2.n>1&&sgn(area(c2.p[(p+1)%c2.n], s, e)-area(c2.p[p%c2.n], s, e))<=0) {
            p++;
        }
        p%=c2.n;
        ans=min(ans,area(c2.p[p], s, e));
    }
    assert(sgn(ans)>0);
    cout<<(ll)((c.getarea()-ans)*2+eps)<<"\n";
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int t=1;
    cin>>t;
    while (t--) {
        solve();
    }
    return 0;
}