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.lang.reflect.Array;
import java.math.BigInteger;
import java.util.*;
import java.util.Map.Entry;

public class abc {

	static int[] parent;
	static long[] size;
	
	public static void main(String[] args) throws NumberFormatException, IOException {
		
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		int n=Integer.parseInt(br.readLine());
		int[][] arr=new int[n][2];
		boolean[][] vis=new boolean[2001][2001];
		for(int i=0 ; i<n ; i++) {
			String[] ss=br.readLine().trim().split(" ");
			arr[i][0]=Integer.parseInt(ss[0])+1000;
			arr[i][1]=Integer.parseInt(ss[1])+1000;
			vis[arr[i][0]][arr[i][1]]=true;
		}
		int count=0;
		for(int i=0 ; i<n ; i++) {
			for(int j=i+1 ; j<n ; j++) {
				int x1=arr[i][0];
				int x3=arr[j][0];
				int y1=arr[i][1];
				int y3=arr[j][1];
				if((x1+x3)%2==0 && (y1+y3)%2==0) {
					int x2=(x1+x3)/2;
					int y2=(y1+y3)/2;
					if(vis[x2][y2]) {
						count++;
					}
				}
				
			}
		}
		System.out.println(count);
	}
}
		