#include<bits/stdc++.h>
#define ll __int128
#define PII pair<int,int>
#define endl '\n'
#define int long long
#define  lc p<<1
#define  rc p<<1|1
using namespace  std;
const int N=1e6+10;
struct point{
    int x, y;
    point() {}
    point operator+(const point &a){
        point rs;
        rs.x=x+a.x;
        rs.y=y+a.y;
        return rs;
    }
    point operator-(const point &a){
        point rs;
        rs.x=x-a.x;
        rs.y=y-a.y;
        return rs;
    }

}p[N],q[N];
bool cmp(point a, point b){return a.x == b.x ? a.y < b.y : a.x < b.x;}
int cross(point a,point b){
    return a.x*b.y-b.x*a.y;
}
int side(point a,point b,point p){
    point A=b-a;
    point B=p-a;
    return cross(A,B);
}
int get_dist(point a,point b){
    return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}

int get_s(point a,point b,point c){
    point A=a-c;
    point B=b-c;
    return cross(A,B);
}

int n,m;
point st[N],st2[N];
int Andrew(int top){
    sort(p+1,p+1+n,cmp);
    if(n<3){
        return -1;
    }
    top=0;
    for (int i = 1; i <=n ; ++i) {
        while(top>1 and side(st[top-1],st[top],p[i])<=0){
            top--;
        }
        st[++top]=p[i];
    }
    int k=top;
    for (int i = n-1; i >=1 ; --i) {
        while(top>k and side(st[top-1],st[top],p[i])<=0)top--;
        st[++top]=p[i];
    }
    if(n>1)top--;
    return top;
}
int Andrew2(int top){
    sort(q+1,q+1+m,cmp);
    if(m<3){
        return -1;
    }
    top=0;
    for (int i = 1; i <=m; ++i) {
        while(top>1 and side(st2[top-1],st2[top],q[i])<=0){
            top--;
        }
        st2[++top]=q[i];
    }
    int k=top;
    for (int i = m-1; i >=1 ; --i) {
        while(top>k and side(st2[top-1],st2[top],q[i])<=0)top--;
        st2[++top]=q[i];
    }
    if(m>1)top--;
    return top;
}

void solve() {
    cin >> n;
    set<PII > vis;
    m = 0;
    for (int i = 1; i <= n; ++i) {
        cin >> p[i].x >> p[i].y;
        vis.insert({p[i].x, p[i].y});
    }
    int d = Andrew(1);
    if (d == -1) {
        cout << "-1\n";
        return;
    }
    for (int i = 1; i <= d; ++i) {
        st[i + d] = st[i];
        // cout<<st[i].x<<' '<<st[i].y<<endl;
    }
    for (int i = 1; i <= d; ++i) {
        vis.erase({st[i].x, st[i].y});
    }
    for (int i = 1; i <= n; ++i) {
        if (vis.count({p[i].x, p[i].y})) {
            q[++m] = p[i];
        }
    }
    int res = 0;
    for (int i = 3; i <= d; ++i) {
        res += abs(get_s(st[i], st[i - 1], st[1]));
    }
    if (m == 0) {
        cout << "-1\n";
        return;
    }
    int d2 = Andrew2(0);
    if (d2 == -1) {
        d2 = 0;
        for (int i = 1; i <= m; ++i) {
            st2[++d2] = q[i];
        }
    }
    //cout<<endl;
    for (int i = 1; i <= d2; ++i) {
        st2[i + d2] = st2[i];
        //cout<<st2[i].x<<' '<<st2[i].y<<endl;
    }
    int id = 0;
    int mi = LLONG_MAX;
    for (int i = 1; i <= d2; ++i) {
        int dq = abs(get_s(st[1], st[2], st2[i]));
        if (dq <= mi) {
            mi = dq;
            id = i;
        }
    }
    res = abs(res);
//    cout<<id<<endl;
//    cout<<st2[id].x<<' '<<st2[id].y<<endl;
    int l = id;
    int rs = 0;
    for (int i = 2; i <=d + 1; ++i) {
        mi = abs(get_s(st[i-1], st[i], st2[l]));
        while ( mi > abs(get_s(st[i-1], st[i], st2[l%d2+1]))) {
            mi = abs(get_s(st[i-1], st[i], st2[l%d2+1]));
            l=l%d2+1;
        }
        rs = max(rs, res - mi);
    }
    cout << rs << endl;
    for (int i = 1; i <= d * 2; ++i) {
        st[i].x = 0;
        st[i].y = 0;
    }
    for (int i = 1; i <= d2 * 2; ++i) {
        st2[i].x = 0;
        st2[i].y = 0;
    }

}
signed main(){
    ios::sync_with_stdio(false),cin.tie(0);
    int t=1;
    cin>>t;
    while(t--){
        solve();
    }
}