#include<bits/stdc++.h>
#define endl "\n"
#define ll long long
#define int long long
using namespace std;
#define pii pair<int, int>
#define rep(i, a, b) for(int i = a; i <= b; i ++ )
#define pre(i, a, b) for(int i = a; i >= b; i -- )
#define IOS ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
const int N = 1e6 + 10;
int n, m, k, tot;
struct Point
{
    int x, y;
    int id;
}p[N], ji, pp[N];
int cmp1(Point x,Point y){
    return x.x!=y.x ? x.x<y.x : x.y<y.y;
}
int cross(Point a,Point b,Point c){ //叉积
  return (b.x-a.x)*(c.y-a.y)-(b.y-a.y)*(c.x-a.x);
}
int stk[N], tp = 0, st[N], ff[N], ttp;
void tubao(){
    sort(p + 1, p + n + 1, cmp1);
    for(int i=1;i<=n;i++){
    while(tp>1&&cross(p[stk[tp-1]],p[stk[tp]],p[i])<=0)tp--;
    stk[++tp]=i;
    }
    int t=tp;
    for(int i=n-1;i>=1;i--){
    while(tp>t&&cross(p[stk[tp-1]],p[stk[tp]],p[i])<=0)tp--;
    stk[++tp]=i;
    }
}
void tubao2(){
    sort(pp + 1, pp + tot + 1, cmp1);
    for(int i=1;i<=tot;i++){
    while(ttp>1&&cross(pp[st[ttp-1]],pp[st[ttp]],pp[i])<=0)ttp--;
    st[++ttp]=i;
    }
    int t=ttp;
    for(int i=tot-1;i>=1;i--){
    while(ttp>t&&cross(pp[st[ttp-1]],pp[st[ttp]],pp[i])<=0)ttp--;
    st[++ttp]=i;
    }
}
void solve()
{
    tot = 0;
    tp = 0;
    ttp = 0;
    cin >> n;
    rep(i, 1, n) cin >> p[i].x >> p[i].y, ff[i] = 0;
    tubao();
    rep(i, 1, tp - 1)
    {
        ff[stk[i]] = 1;
        // cout<<p[stk[i]].x<<" "<<p[stk[i]].y<<endl;
    }
    rep(i, 1, n) if(!ff[i]) pp[++tot] = p[i];
    int ans = 0, res = 0;
    rep(i, 2, tp - 2)
    {
        ans += cross(p[stk[1]], p[stk[i]], p[stk[i + 1]]);
    }
    // cout << ans << endl;
    if(tot >= 3)
    {
        tubao2();
        // rep(i, 1, ttp - 1)
        // {
        //     cout<<pp[st[i]].x<<" "<<pp[st[i]].y<<endl;
        // }
        rep(i, 2, tp - 1)
        {
            res += cross(pp[st[0]], pp[st[i]], pp[st[i + 1]]);
        }
        int last = 1;
        int anss = 0;
        rep(i, 1, tp - 1)
        {
            int l = i, r = i + 1, s = 1e9;
            while(1)
            {

                if(s == 1e9) 
                {
                    s = cross(p[stk[l]], p[stk[r]], pp[st[last]]);
                }
                else if(cross(p[stk[l]], p[stk[r]], pp[st[(last + 1) == ttp ? 1 : (last + 1)]]) < s)
                {
                    last ++ ;
                    if(last == ttp) last = 1; 
                    s = cross(p[stk[l]], p[stk[r]], pp[st[last]]);
                }
                else if(cross(p[stk[l]], p[stk[r]], pp[st[(last + 1) == ttp ? 1 : (last + 1)]]) >= s)
                {
                    break;
                }
            }
            // cout<<i<<" "<<pp[st[last]].x<<" "<<pp[st[last]].y<<endl;
            anss = max(anss, ans - s);
        }
        cout << anss << endl;
    }
    else if(!tot) cout << -1 << endl;
    else
    {
        // cout<<cross({0,4},{-2,0},{5,2});
        int anss = 0;
        rep(i, 1, tp - 1)
        {
            int l = i, r = i + 1;
            if(r == tp) r = 1;
            rep(j, 1, tot)
            {
                res = cross(p[stk[l]], p[stk[r]], pp[j]);
                anss = max(anss, ans - res);
            }
        }
        cout << anss << endl;
    }
}
signed main()
{
    IOS;
    int _;
    _ = 1;
    cin >> _;
    while(_ -- )
    {
        solve();
    }
	return 0;
}