#include<bits/stdc++.h>

 using namespace std;

 const int maxn=;

 typedef int db;

 struct Point

 {

     /*点类*/

     db x,y;

     Point(){}

     Point(db _x,db _y):x(_x),y(_y){}

     void input()

     {

         scanf("%d%d",&x,&y);

     }

     Point operator + (const Point &t)const

     {

         return Point(x+t.x,y+t.y);

     }

     Point operator - (const Point &t)const

     {

         return Point(x-t.x,y-t.y);

     }

     db operator * (const Point &t)const

     {

         return x*t.y-y*t.x;

     }

     db len()const

     {

         return x*x+y*y;

     }

     bool operator < (const Point &t) const

     {

         if((*this)*t!=) return (*this)*t>;

         return len()<t.len();

     }

 }p[maxn+],a[maxn+];

 int n,m;

 int ans;

 int dp[maxn+][maxn+],sum[maxn+][maxn+];

 void work(int n)

 {

     memset(dp,,sizeof(dp));

     memset(sum,,sizeof(sum));

     for(int i=;i<=n;++i)

     {

         int j=i-;

         while(j>=&&a[i]*a[j]==) --j;

         bool flag=;

         if(j==i-) flag=;

         while(j>=)

         {

             int k=j-;

             int res=a[j]*a[i];

             while(k>=&&(a[j]-a[i])*(a[k]-a[j])>) --k;

             if(k) res+=sum[j][k];

             if(flag) dp[i][j]=res;

             ans=max(ans,res);

             j=k;

         }

         sum[i][]=dp[i][];

         for(int j=;j<i;++j) sum[i][j]=max(dp[i][j],sum[i][j-]);

     }

 }

 int main()

 {

     int T;

     scanf("%d",&T);

     while(T--)

     {

         scanf("%d",&n);

         for(int i=;i<=n;++i) p[i].input();

         ans=;

         for(int i=;i<=;++i)

         {

             m=;

             for(int j=;j<=n;++j) if(p[j].y>p[i].y||(p[i].y==p[j].y&&p[j].x>=p[i].x)) a[++m]=p[j]-p[i];

             //for(int i=1;i<=m;++i) printf("%d %d\n",a[i].x,a[i].y);

             //printf("\n");

             sort(a+,a+m+);

             //for(int i=1;i<=m;++i) printf("%d %d\n",a[i].x,a[i].y);

             work(m);

         }

         //printf("%d\n",ans);

         printf("%.1f\n",1.0*ans/);

     }

     return ;

 }