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.Arrays;
import java.util.Scanner;

public class B {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		xb[] x = new xb[n];
		// yb[] y = new yb[n];
		for (int i = 0; i < n; i++) {
			// x[i] = new xb();
			x[i] = new xb();
			x[i].x = sc.nextInt();
			x[i].y = sc.nextInt();
			// x[i].num = i;
			// y[i].x = x[i].x;
			// y[i].y = x[i].y;
			// y[i].num = i;
		}
		Arrays.sort(x);
		// Arrays.sort(y);
		int s = 0;
		for (int i = 0; i < n; i++) {

			for (int j = i + 2; j < n; j++) {
				int xm = (x[i].x + x[j].x), ym = x[i].y + x[j].y;
				if (xm % 2 != 0 || ym % 2 != 0)
					continue;
				xm /= 2;
				ym /= 2;
				for (int k = i; k < n; k++) {
					if (xm == x[k].x && ym == x[k].y) {
						// if (xm == x[k].x && ym == x[k].y)
						s++;
						break;
					} else if (xm > x[k].x || ym > x[k].y)
						break;
				}
			}
		}
		System.out.println(s);
	}

}

class xb implements Comparable<xb> {
	int x, y, num;

	@Override
	public int compareTo(xb o) {
		return o.x - x;
	}

}

// class yb implements Comparable<yb> {
// int x, y, num;
//
// @Override
// public int compareTo(yb o) {
// return o.y - y;
// }
//
// }
