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.*;
import java.lang.*;
import java.io.*;

public class triplets {
    public static void main(String[] args) throws java.lang.Exception {
        // your code goes here
        //try {
            // Scanner sc=new Scanner(System.in);
            FastReader sc = new FastReader();
            int t =1;// sc.nextInt();
            while (t-- > 0) {
                int n=sc.nextInt();
                boolean[][] totPoints=new boolean[2001][2001];
                int[][] points=new int[n][2];
                for(int i=0;i<n;i++){
                    int x=sc.nextInt()+1000;
                    int y=sc.nextInt()+1000;
                    totPoints[x][y]=true;
                    points[i][0]=x;
                    points[i][1]=y;
                }
                int tripletsCount=0;
                for(int i=0;i<n-1;i++){
                    int x1=points[i][0];
                    int y1=points[i][1];
                    for(int j=i+1;j<n;j++){
                        int x2=points[j][0];
                        int y2=points[j][1];
                        int x3=x1+x2;
                        int y3=y1+y2;
                        if(x3%2==0 && y3%2==0){
                            if(totPoints[x3/2][y3/2]){
                                tripletsCount++;
                            }
                        }
                    }
                }
                System.out.println(tripletsCount);
            }
       /* } catch (Exception e) {
            return;
        }*/

    }
    

    static int BS(int[] arr, int l, int r, int element) {
        int low = l;
        int high = r;
        while (high - low > 1) {
            int mid = low + (high - low) / 2;
            if (arr[mid] < element) {
                low = mid + 1;
            } else {
                high = mid;
            }
        }
        if (arr[low] == element) {
            return low;
        } else if (arr[high] == element) {
            return high;
        }
        return -1;
    }

    static int lower_bound(int[] arr, int l, int r, int element) {
        int low = l;
        int high = r;
        while (high - low > 1) {
            int mid = low + (high - low) / 2;
            if (arr[mid] < element) {
                low = mid + 1;
            } else {
                high = mid;
            }
        }
        if (arr[low] >= element) {
            return low;
        } else if (arr[high] >= element) {
            return high;
        }
        return -1;
    }

    static int upper_bound(int[] arr, int l, int r, int element) {
        int low = l;
        int high = r;
        while (high - low > 1) {
            int mid = low + (high - low) / 2;
            if (arr[mid] <= element) {
                low = mid + 1;
            } else {
                high = mid;
            }
        }
        if (arr[low] > element) {
            return low;
        } else if (arr[high] > element) {
            return high;
        }
        return -1;
    }

    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        String nextLine() {
            String s = "";
            try {
                s = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return s;
        }

        Long nextLong() {
            return Long.parseLong(next());
        }
    }
}

/*
 * public static boolean lie(int n,int m,int k){ if(n==1 && m==1 && k==0){
 * return true; } if(n<1 || m<1 || k<0){ return false; } boolean
 * tc=lie(n-1,m,k-m); boolean lc=lie(n,m-1,k-n); if(tc || lc){ return true; }
 * return false; }
 */

