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.Scanner;

public class Main {

	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		boolean[][] plane = new boolean[2001][2001];
		int n = sc.nextInt();
		int u, v;
		for (int i = 0; i < n; i++) {
			u = sc.nextInt();
			v = sc.nextInt();
			plane[u + 1000][v + 1000] = true;
		}
		
		int sum  = 0;
		int x3, y3;
		for (int x1 = 0; x1 < 2001; x1++) {
			for (int y1 = 0; y1 < 2001; y1++) {
				if (plane[x1][y1]) {
					for (int x2 = 0; x2 < 2001; x2++) {
						for (int y2 = 0; y2 < 2001; y2++) {
							if ((plane[x2][y2]) && (x1 != x2) && (y1 != y2) && ((x1 + x2) % 2 == 0) && ((y1 + y2) % 2 == 0)) {
								x3 = (x1 + x2) / 2;
								y3 = (y1 + y2) / 2;
								if (plane[x3][y3]) sum++;
							}
						}
					}
				}	
			}
		}
		
		System.out.println(sum / 2);
	}

}
