fzu 1302
#include<iostream>
#include<algorithm>
#include<cmath>
#define eps 1e-8
using namespace std;
struct pt
{
    double x,y;
}p1[50010],p2[50010];
int dblcmp(double x)
{
    if(fabs(x)<eps)
        return 0;
    return x<0?-1:1;
}
double cross(pt a,pt b,pt c)
{
    return (b.x-a.x)*(c.y-a.y)-(c.x-a.x)*(b.y-a.y);
}
double dist(pt a,pt b)
{
    return (a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y);
}
bool cmp(pt a,pt b)
{
    int t=dblcmp(cross(p1[0],a,b));
    if(t==0)
        return dist(p1[0],a)<dist(p1[0],b);
    else return t>0; 
}
int n;
int Tubao()
{
    int swap=0;
    int i;
    for(i=1;i<n;i++)
        if(p1[i].y<p1[swap].y||(p1[i].y==p1[swap].y&&p1[i].x<p1[swap].x))
            swap=i;
    p2[0]=p1[0];
    p1[0]=p1[swap];
    p1[swap]=p2[0];
    sort(p1+1,p1+n,cmp);
    p2[0]=p1[0];
    p2[1]=p1[1];
    int top=1;
    for(i=2;i<n;i++)
    {
        while(top>0&&dblcmp(cross(p2[top-1],p2[top],p1[i]))<=0)
            top--;
        p2[++top]=p1[i];
    }
    return top+1;
}
int main()
{
    int i,j,k;
    while(scanf("%d",&n)!=EOF)
    {        
        if(n==-1)
            break;
        for(i=0;i<n;i++)
        {
            scanf("%lf%lf",&p1[i].x,&p1[i].y);
        }
        if(n <= 2){
            printf("0.00\n");
            continue;      
        }
        if(n == 3){
            printf("%.2lf\n", fabs(cross(p1[0], p1[1], p1[2]))/2);
            continue; 
        }
        n=Tubao();
        double best=-1;
        double area2;
        for(i=0;i<=n-3;i++)//O(n^2)利用峰值原理，以某条边为底边枚举点旋转有一个最大面积峰值。到峰值后旋转底边，再继续旋转点，到峰值再旋转……
        {
            k=0;
            for(j=i+1;j<=n-2;j++)
            {
                if(k<=j)
                    k=j+1;
                area2=fabs(cross(p2[i],p2[j],p2[k]));
                if(area2>best)
                    best=area2;
                while(k+1<=n-1)
                {
                    double tmp=fabs(cross(p2[i],p2[j],p2[k+1]));
                    if(tmp<area2)
                        break;
                    best=max(best,tmp);
                    area2=tmp;
                    k++;
                }                        
            }
        }
        printf("%.2f\n",best/2);
    }    
}