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.util.Arrays;
import java.util.Scanner;


public class first {

    /**
     * @param args
     */
    
    class point implements Comparable{
        int x;
        int y;
        @Override
        public int compareTo(Object arg0) {
            point s=(point)arg0;
            if (this.x<s.x)
            return -1;
            else
                if (this.x==s.x)
                    if (this.y<s.y)
                        return -1;
                    else
                        if (this.y==s.y)
                        return 0;
        return 1;
        }
    }
    public static void main(String[] args) {
           Scanner sc=new Scanner(System.in);
           int n=sc.nextInt();
           point[] points=new point[n];  
           for (int i=0; i<n; i++)
           {
            point a=new first().new point();
            a.x=sc.nextInt();
            a.y=sc.nextInt();
            points[i]=a;
           }
           Arrays.sort(points);
           int cnt=0;
           for (int i=0; i<n; i++)
               for (int j=i+2; j<n; j++)
               { 
                   int middlx,middly;
                   if ((points[i].x+points[j].x)%2!=0)
                       continue;
                   else
                    middlx=(points[i].x+points[j].x)/2;
                   if ((points[i].y+points[j].y)%2!=0)
                       continue;
                   else
                    middly=(points[i].y+points[j].y)/2;
                   point find=new first().new point();
                   find.x=middlx;
                   find.y=middly;
                   if (Arrays.binarySearch(points, find)>0)
                   {
                    cnt++;   
                   }
               }
           System.out.print(cnt);
               }
    }
