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.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class NumberOfTriplets {
	public static void main(String[] args) {
		PrintWriter pw = new PrintWriter(System.out);
	    reader(System.in);
	    int n = nI();
	    boolean[][] arr = new boolean[2001][2001];
	    int[][] points = new int[n][2];
	    for (int i = 0; i < n; i++) {
	    	int x = nI() + 1000;
	    	int y = nI() + 1000;
	    	points[i][0] = x;
	    	points[i][1] = y;
	    	arr[x][y] = true;
	    }
	    int cnt = 0;
	    for (int i = 0; i < n; i++) {
	    	for (int j = i + 1; j < n; j++) {
	    		int x = (points[i][0] + points[j][0]) / 2;
	    		int y = (points[i][1] + points[j][1]) / 2;
	    		if (x != points[i][0] && x != points[j][0] && y != points[i][1] && y != points[j][1] && arr[x][y])
	    			cnt++;
	    	}
	    }
	    pw.println(cnt);
	    pw.close();
	}
	
	private static BufferedReader br;
	private static StringTokenizer st;

	static void reader(InputStream stream) {
	    try {
	        br = new BufferedReader(new InputStreamReader(stream));
	    } catch (Exception e) {
	        e.printStackTrace();
	    }
	}

	static String n() {
	    while (st == null || !st.hasMoreTokens()) {
	        try {
	            st = new StringTokenizer(br.readLine());
	        } catch (IOException e) {
	            e.printStackTrace();
	        }
	    }
	    return st.nextToken();
	}

	static int nI() {
	    return Integer.parseInt(n());
	}
	
	static long nL() {
	    return Long.parseLong(n());
	}
}