10
-2 1
2 -2
-1 -2
0 0
2 -1
0 -2
2 2
0 2
-1 -1
1 -2
 40
-8 24
2 -1
1 -18
72 -70
5 -4
-308 436
-19 40
36 -35
-178 265
-1 2
-7 30
-1 0
3 -2
200 -285
17 -16
-35 74
0 -4
-86 106
-1 4
-7 6
0 1
-5 4
-2 3
6 -5
-4 5
181 -262
76 -118
0 0
-7 18
-58 104
-5 6
-6 12
-3 4
1 0
11 -10
-86 130
-3 6
153 -236
-183 270
-33 64
 5
0 -1
0 -2
0 -3
0 -4
0 -5
 10
0 1
-1 -1
1 1
-1 0
1 -1
-2 -1
-2 2
-2 0
0 -2
0 -1
 20
-1 18
-2 5
-5 4
2 -33
9 -18
0 0
11 -22
2 0
-1 2
-4 41
1 6
1 -2
6 -12
0 1
-3 6
3 -6
3 -8
-1 4
2 -5
1 0
 10
2 1
-1 0
-2 -1
-1 1
0 2
2 -2
0 0
-2 -2
0 -2
-2 1
 20
-3 -3
0 4
-3 1
1 1
-1 2
-4 4
3 -1
-3 0
0 2
4 0
2 3
2 4
4 -3
-4 3
-1 1
1 3
-2 4
1 -2
1 -1
3 0
 3
0 0
0 -1
0 1
 10
2 1
-1 1
0 0
-3 1
-2 -3
-1 -2
-1 -1
1 2
3 -2
0 -2
 3
3 3
1 2
1 1
 4
0 0
1 0
2 0
3 0
 9
1 1
1 0
0 1
0 0
-1 0
-1 1
-1 -1
1 -1
0 -1
 7
1 1
-1 -1
1 0
0 1
-1 0
0 -1
0 0

4
 57
 4
 5
 21
 4
 10
 1
 1
 0
 2
 8
 3

import java.io.*;
import java.util.*;
import java.lang.Math.*;
public class crocB
{
     public static void main(String args[])throws Exception
     {
         Scanner in=new Scanner(System.in);
         //BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
         //BufferedReader br = new BufferedReader(new FileReader("crockB.in"));
         //PrintWriter pw = new PrintWriter(new BufferedWriter(new FileWriter("crockB.out")));
         PrintWriter pw = new PrintWriter(System.out);
         //StringTokenizer st;
         int n=in.nextInt();
         int i,j,k=0,l=0,ctr=0;
         int a[][]=new int[n][2];
         int b[][]=new int[2010][2010];
         /*for(i=0;i<2010;i++)
         for(j=0;j<2010;j++)
         b[i][j]=-999999999;*/
         for(i=0;i<n;i++)
         {
            a[i][0]=in.nextInt()+1001;
            a[i][1]=in.nextInt()+1001;
            b[a[i][0]][a[i][1]]++;
         }
         for(i=0;i<n;i++)
         {
             for(j=i+1;j<n;j++)
             {
                 k=2*a[i][0]-a[j][0];
                 l=2*a[i][1]-a[j][1];
             
             if(k<2010 && l<2020 && b[k][l]!=0)
             {
                 if(b[k][l]!=10000*a[i][0]+a[i][1] || b[a[j][0]][a[j][1]]!=10000*a[i][0]+a[i][1])     
                     {
                         ctr++;
                         b[a[j][0]][a[j][1]]=10000*a[i][0]+a[i][1];
                        b[k][l]=10000*a[i][0]+a[i][1];
                    }
             }
               
            }
 
        }
         
        pw.println(ctr);
        pw.flush();
       //pw.close();
        System.exit(0);
     }
}