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.util.*;
public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(in.readLine().trim());
		Point[] points = new Point[n];
		TreeMap<Point, Integer> set = new TreeMap<>();
		TreeSet<Triple> tri = new TreeSet<>();
		for(int i = 0; i < n; i++){
			String[] arr = in.readLine().trim().split(" ");
			Point p = new Point(Integer.parseInt(arr[0]), Integer.parseInt(arr[1]), i);
			points[i] = p;
			set.put(p, p.i);
		}
		
		for(int i = 0; i < n - 1; i++){
			for(int j = i + 1; j < n; j++){
				Point p1 = get(points[i], points[j]);
				Point p2 = get(points[j], points[i]);
				if(set.containsKey(p1))
					tri.add(new Triple(points[i].i, points[j].i, set.get(p1)));
				if(set.containsKey(p2))
					tri.add(new Triple(points[i].i, points[j].i, set.get(p2)));
			}
		}
		System.out.println(tri.size());
	}
	public static Point get(Point p1, Point p2){
		return new Point(2 * p2.x - p1.x, 2 * p2.y - p1.y, -1);
	}

}
class Point implements Comparable<Point>{
	int x;
	int y;
	int i;
	Point(int xx, int yy, int ii){
		x = xx;
		y = yy;
		i = ii;
	}
	public int compareTo(Point p){
		if(x == p.x)
			return y - p.y;
		else
			return x - p.x;
	}
}
class Triple implements Comparable<Triple>{
	int i, j, k;
	public Triple(int ii, int jj, int kk){
		int[] arr = new int[3];
		arr[0] = i; arr[1] = j; arr[2] = k;
		Arrays.sort(arr);
		i = arr[0]; j = arr[1]; k = arr[2];
	}
	public int compareTo(Triple t){
		if(i == t.i){
			if(j == t.j){
				if(k == t.k)
					return 0;
				else
					return k - t.k;
			}
			else
				return j - t.j;
		}
		else
			return i - t.i;
	}
}