#include <iostream>

 #include <stdio.h>

 #include <string.h>

 #include <math.h>

 #include <stdlib.h>

 using namespace std;

 #define MX 35

 struct Mat

 {

     int a,b,c,d;

     int area;

 }mat[];

 int n;

 int x[MX];

 int y[MX];

 int G[][];

 int check(int u,int v)

 {

     int xxx = min(min(x[mat[u].a],x[mat[u].b]),min(x[mat[u].c],x[mat[u].d]));

     int xxy = min(min(y[mat[u].a],y[mat[u].b]),min(y[mat[u].c],y[mat[u].d]));

     int ddx = max(max(x[mat[u].a],x[mat[u].b]),max(x[mat[u].c],x[mat[u].d]));

     int ddy = max(max(y[mat[u].a],y[mat[u].b]),max(y[mat[u].c],y[mat[u].d]));

     int xx = min(min(x[mat[v].a],x[mat[v].b]),min(x[mat[v].c],x[mat[v].d]));

     int xy = min(min(y[mat[v].a],y[mat[v].b]),min(y[mat[v].c],y[mat[v].d]));

     int dx = max(max(x[mat[v].a],x[mat[v].b]),max(x[mat[v].c],x[mat[v].d]));

     int dy = max(max(y[mat[v].a],y[mat[v].b]),max(y[mat[v].c],y[mat[v].d]));

     if (xxx>dx||xxy>dy||ddx<xx||ddy<xy)//在 右上左下

         return mat[v].area+mat[u].area;

     if (xxx>xx&&ddx<dx&&xxy>xy&&ddy<dy)//包含

         return max(mat[v].area,mat[u].area);

     if (xxx<xx&&ddx>dx&&xxy<xy&&ddy>dy)

         return max(mat[v].area,mat[u].area);

     return ;

 }

 int main()

 {

     while (scanf("%d",&n)&&n)

     {

         memset(G,-,sizeof(G));

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

         {

             scanf("%d%d",&x[i],&y[i]);

             G[x[i]][y[i]]=i;

         }

         int m=;

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

         {

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

             {

                 if (x[i]==x[j]||y[i]==y[j]) continue;

                 int fir,sec;

                 if (G[x[i]][y[j]]!=-) fir=G[x[i]][y[j]];

                 else continue;

                 if (G[x[j]][y[i]]!=-) sec=G[x[j]][y[i]];

                 else continue;

                 int lon=abs(x[i]-x[j]);

                 int kua=abs(y[i]-y[j]);

                 mat[m++]=(Mat){fir,sec,i,j,lon*kua};

             }

         }

         int ans = ;

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

         {

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

             {

                 ans = max(ans,check(i,j));

             }

         }

         if (ans!=)

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

         else

             printf("imp\n");

     }

     return ;

 }