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

/**
 * Created with IntelliJ IDEA.
 * User: Zakhar_Voit
 * Date: 21.04.12
 * Time: 1:48
 */

import java.io.*;
import java.util.*;

import static java.lang.System.exit;

public class B {
    BufferedReader in;
    PrintWriter out;
    StringTokenizer st = new StringTokenizer("");

    int n, ans = 0;

    int[] x, y;
    boolean[][] used;

    public void openIO() throws IOException {
        if (new File("input.txt").exists()) {
            System.setIn(new FileInputStream("input.txt"));
            out = new PrintWriter(new BufferedWriter(new FileWriter("output.txt")));
        } else {
            out = new PrintWriter(System.out);
        }
        in = new BufferedReader(new InputStreamReader(System.in));
    }

    String nextToken() throws IOException {
        while (!st.hasMoreTokens())
            st = new StringTokenizer(in.readLine());
        return st.nextToken();
    }

    int nextInt() throws IOException {
        return Integer.parseInt(nextToken());
    }

    long nextLong() throws IOException {
        return Long.parseLong(nextToken());
    }

    double nextDouble() throws IOException {
        return Double.parseDouble(nextToken());
    }

    String nextLine() throws IOException {
        st = new StringTokenizer("");
        return in.readLine();
    }

    boolean EOF() throws IOException {
        while (!st.hasMoreTokens()) {
            String s = in.readLine();
            if (s == null)
                return true;
            st = new StringTokenizer(s);
        }
        return false;
    }

    void init() {

    }

    void read() throws IOException {
        n = nextInt();
        x = new int[n];
        y = new int[n];
        used = new boolean[8000][8000];
        for (int i = 0; i < n; i++) {
            x[i] = nextInt(); y[i] = nextInt();
            used[x[i] + 2000][y[i] + 2000] = true;
        }
    }

    void solve() {
        for (int i = 0; i < n; i++) {
            for (int j = i + 1; j < n; j++) {
                int middlex = (x[i] + x[j])/2, middley = (y[i] + y[j])/2;
                if ((x[i] + x[j])%2 != 0 || (y[i] + y[j])%2 != 0) continue;
                if (used[middlex + 2000][middley + 2000] && middlex != x[i] && middlex != x[j] && middley != y[i] && middley != y[j]) ans++;
            }
        }
    }

    void write() {
        out.println(ans);
    }

    public void run() throws IOException {
        openIO();
        init();
        read();
        solve();
        write();
        out.close();
    }

    static public void main(String[] args) throws IOException {
        new Thread(null, new Runnable() {
            public void run() {
                try {
                    new B().run();
                } catch (Throwable e) {
                    e.printStackTrace();
                    exit(999);
                }
            }
        }, "1", 1 << 23).start();
    }
}