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.*;
public class cf181b {
  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    int n = in.nextInt();
    vec2[] v = new vec2[n];
    Set<vec2> set = new TreeSet<vec2>();
    for(int i=0; i<n; i++)
      set.add(v[i] = new vec2(in.nextInt(),in.nextInt()));
    int ans = 0;
    for(int i=0; i<n; i++)
      for(int j=0; j<i; j++) {
        vec2 tmp = v[i].add(v[j]);
        if(!tmp.ok()) continue;
        tmp.divide();
        if(set.contains(tmp)) ans++;
      }
    System.out.println(ans);
  }
  static class vec2 implements Comparable<vec2> {
    int x,y;
    vec2(int a, int b) {
      x=a;y=b;
    }
    vec2 add(vec2 v) {
      return new vec2(x+v.x,y+v.y);
    }
    vec2 divide() {
      return new vec2(x/2,y/2);
    }
    boolean ok() {
      return (x&1)==1 && (y&1)==1;
    }
    public int compareTo(vec2 v) {
      if(x == v.x) return y-v.y;
      return x-v.x;
    }
  }
}
