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 static java.lang.Math.*;
import static java.lang.System.out;

public class Main {
	Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		new Main().B();
	}
	
	int[] x,y;
	void B(){
		int n=sc.nextInt();
		x=new int[n];
		y=new int[n];
		for(int i=0; i<n; i++){
			x[i]=sc.nextInt();
			y[i]=sc.nextInt();
		}
		int ans=0;
		for(int i=0; i<n; i++){
			for(int j=0; j<n; j++){
				if(i==j)	continue;
				ans+=solveB(x[i],y[i],x[j],y[j])?1:0;
			}
		}
		out.println(ans/2);
	}
	boolean solveB(int ax, int ay, int cx, int cy){
		boolean ans=false;
		int xx=ax,yy=ay;
		if(((cx-ax)/2.0)%1==0 && ((cy-ay)/2.0)%1==0){
			xx+=(cx-ax)/2;
			yy+=(cy-ay)/2;
			int bi=-1;
			for(int i=0; i<x.length; i++){
				if(x[i]==xx){
					bi=i;
					break;
				}
			}
			//int bi=Arrays.binarySearch(x,xx);
			//out.println("xx"+xx+" yy"+yy+" : ax"+ax+" ay"+ay+" : cx"+cx+" cy"+cy+" bi"+bi);
			if(bi>=0){
				if(y[bi]==yy){
					//out.println("xx"+xx+" yy"+yy+" : ax"+ax+" ay"+ay+" : cx"+cx+" cy"+cy);
					ans=true;
				}
			}
		}
		return ans;
	}
	
	void A(){
		int row=sc.nextInt(), col=sc.nextInt();
		int[] c=new int[col+1], r=new int[row+1];
		for(int i=1; i<=row; i++){
			char[] ch = sc.next().toCharArray();
			for(int j=1; j<=col; j++){
				if(ch[j-1]=='*'){
					c[j]++;	r[i]++;
				}
			}
		}
		for(int i=1; i<=row; i++)	if(r[i]==1)	out.print(i);
		out.print(" ");
		for(int i=1; i<=col; i++)	if(c[i]==1)	out.print(i);
		out.println();
	}
	
}
