#include<bits/stdc++.h>
#ifdef LOCAL
#define debug(...) printf(__VA_ARGS__)
#define edebug(...) fprintf(stderr, __VA_ARGS__)
#else
#define debug(...)
#define edebug(...)
#endif
#define int __int128
#define rep(i, x, y) for(int i = x; i <= y; ++i)
#define nrep(i, x, y) for(int i = x; i >= y; --i)
#define ll long long
#define pii std::pair<int,int>
#define pb emplace_back
#define fi first
#define se second
template <class T> 
inline void ckmax(T &a, T b) {
  if(a < b) a = b;
}
template <class T> 
inline void ckmin(T &a, T b) {
  if(a > b) a = b;
}
auto rt_YES = []{puts("YES");};
auto rt_Yes = []{puts("Yes");};
auto rt_NO = []{puts("NO");};
auto rt_No = []{puts("No");};
namespace IO {
#define isdigit(x) (x >= '0' && x <= '9')
  inline char gc() {
    return getchar();
  }
  inline bool blank(char ch) {
    return ch == ' ' || ch == '\n' || ch == '\r' || ch == '\t';
  }
  template <class T>
  inline void read(T &x) {
    double tmp = 1;
    bool sign = 0;
    x = 0;
    char ch = gc();
    for(; !isdigit(ch); ch = gc())
      if(ch == '-') sign = 1;
    for(; isdigit(ch); ch = gc())
      x = x * 10 + (ch - '0');
    if(ch == '.')
      for(ch = gc(); isdigit(ch); ch = gc())
        tmp /= 10.0, x += tmp * (ch - '0');
    if(sign) x = -x;
  }
  inline void read(char *s) {
    char ch = gc();
    for(; blank(ch); ch = gc());
    for(; !blank(ch); ch = gc())
      *s++ = ch;
    *s = 0;
  }
  inline void read(char &c) {
    for(c = gc(); blank(c); c = gc());
  }
  inline void push(const char &c) {
    putchar(c);
  }
  template <class T>
  inline void print(T x) {
    if(x < 0) {
      x = -x;
      push('-');
    }
    static T sta[35];
    T top = 0;
    do {
      sta[top++] = x % 10;
      x /= 10;
    } while(x);
    while(top)
      push(sta[--top] + '0');
  }
  template <class T>
  inline void print(T x, char lastChar) {
    print(x);
    push(lastChar);
  }
}
using namespace IO;

struct Point
{
    int x, y;
    Point() {}
    Point(int _x, int _y) : x(_x), y(_y) {}
    void operator=(pii A) { x = A.fi, y = A.se;}
    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); }

    int operator^(const Point &b) const { return x * b.y - y * b.x; } //叉积
    int operator*(const Point &b) const { return x * b.x + y * b.y; } //点积

    bool operator<(const Point &b) const { return x < b.x || (x == b.x && y < b.y); }
    bool operator==(const Point &b) const { return x - b.x == 0 && y - b.y == 0; }

} p[100010], h1[100010], h2[100010];
inline int CalcArea(Point p[], int n)
{
    int res = 0;
    for (int i = 0; i < n; i++)
        res += (p[i] ^ p[(i + 1) % n]);
    return (res>0?res:-res);
}
inline int TriangleArea(Point x, Point y, Point z) {
  Point P[3]={x,y,z};
  return CalcArea(P,3);
}
int ConvexHull(Point *p, int n, Point *ch) //求凸包
{
    std::sort(p, p + n);
    n = std::unique(p, p + n) - p; //去重
    int m = 0;
    for (int i = 0; i < n; ++i)
    {
        while (m > 1 && ((ch[m - 1] - ch[m - 2]) ^ (p[i] - ch[m - 1])) <= 0)
            --m;
        ch[m++] = p[i];
    }
    int k = m;
    for (int i = n - 2; i >= 0; i--)
    {
        while (m > k && ((ch[m - 1] - ch[m - 2]) ^ (p[i] - ch[m - 1])) <= 0)
            --m;
        ch[m++] = p[i];
    }
    if (n > 1)
        m--;
    return m;
}

std::map<pii,int>mp;
void solve(){
  int n;read(n);mp.clear();
  rep(i,0,n-1)read(p[i].x),read(p[i].y),mp[{p[i].x,p[i].y}]=1;
  int N=ConvexHull(p,n,h1);int Sz=CalcArea(h1,N);
  rep(i,0,N-1)mp.erase({h1[i].x,h1[i].y});
  int cnt=0;
  for(auto[x,y]:mp)p[cnt++]=std::make_pair(x.fi,x.se);
  if(cnt==0){puts("-1");return;}
  int M=ConvexHull(p,cnt,h2),cur=0,ans=1e30;
  rep(k,0,100)
  rep(i,0,N-1){
    while(TriangleArea(h2[cur%M],h1[i],h1[(i+1)%N])>TriangleArea(h2[(cur+1)%M],h1[i],h1[(i+1)%N])){
      ckmin(ans,TriangleArea(h2[cur%M],h1[i],h1[(i+1)%N]));
      ++cur;
    }
    ckmin(ans,TriangleArea(h2[cur%M],h1[i],h1[(i+1)%N]));
  }
  print(Sz-ans,'\n');
}

signed main() {
  clock_t c1 = clock();
#ifdef LOCAL
  freopen("in.in", "r", stdin);
  freopen("out.out", "w", stdout);
#endif
//------------------------------------------------------------------

  int t;read(t);while(t--)solve();

//------------------------------------------------------------------
end:
  std::cerr << "Time : " << clock() - c1 << " ms" << std::endl;
  return 0;
}