1 #include <iostream>
 2 #include <stdio.h>
 3 #include <string.h>
 4 #include <math.h>
 5 #include <stdlib.h>
 6 using namespace std;
 7 #define MX 35
 8 struct Mat
 9 {
10     int a,b,c,d;
11     int area;
12 }mat[5000];
13
14 int n;
15 int x[MX];
16 int y[MX];
17 int G[205][205];
18
19 int check(int u,int v)
20 {
21     int xxx = min(min(x[mat[u].a],x[mat[u].b]),min(x[mat[u].c],x[mat[u].d]));
22     int xxy = min(min(y[mat[u].a],y[mat[u].b]),min(y[mat[u].c],y[mat[u].d]));
23     int ddx = max(max(x[mat[u].a],x[mat[u].b]),max(x[mat[u].c],x[mat[u].d]));
24     int ddy = max(max(y[mat[u].a],y[mat[u].b]),max(y[mat[u].c],y[mat[u].d]));
25
26     int xx = min(min(x[mat[v].a],x[mat[v].b]),min(x[mat[v].c],x[mat[v].d]));
27     int xy = min(min(y[mat[v].a],y[mat[v].b]),min(y[mat[v].c],y[mat[v].d]));
28     int dx = max(max(x[mat[v].a],x[mat[v].b]),max(x[mat[v].c],x[mat[v].d]));
29     int dy = max(max(y[mat[v].a],y[mat[v].b]),max(y[mat[v].c],y[mat[v].d]));
30
31
32     if (xxx>dx||xxy>dy||ddx<xx||ddy<xy)//在 右上左下
33         return mat[v].area+mat[u].area;
34
35     if (xxx>xx&&ddx<dx&&xxy>xy&&ddy<dy)//包含
36         return max(mat[v].area,mat[u].area);
37     if (xxx<xx&&ddx>dx&&xxy<xy&&ddy>dy)
38         return max(mat[v].area,mat[u].area);
39
40     return 0;
41 }
42
43 int main()
44 {
45     while (scanf("%d",&n)&&n)
46     {
47         memset(G,-1,sizeof(G));
48         for (int i=0;i<n;i++)
49         {
50             scanf("%d%d",&x[i],&y[i]);
51             G[x[i]][y[i]]=i;
52         }
53         int m=0;
54         for (int i=0;i<n;i++)
55         {
56             for (int j=i+1;j<n;j++)
57             {
58                 if (x[i]==x[j]||y[i]==y[j]) continue;
59                 int fir,sec;
60                 if (G[x[i]][y[j]]!=-1) fir=G[x[i]][y[j]];
61                 else continue;
62                 if (G[x[j]][y[i]]!=-1) sec=G[x[j]][y[i]];
63                 else continue;
64
65                 int lon=abs(x[i]-x[j]);
66                 int kua=abs(y[i]-y[j]);
67                 mat[m++]=(Mat){fir,sec,i,j,lon*kua};
68             }
69         }
70         int ans = 0;
71         for (int i=0;i<m;i++)
72         {
73             for (int j=i+1;j<m;j++)
74             {
75                 ans = max(ans,check(i,j));
76             }
77         }
78         if (ans!=0)
79             printf("%d\n",ans);
80         else
81             printf("imp\n");
82     }
83     return 0;
84 }