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.Arrays;
import java.util.StringTokenizer;

import static java.lang.Math.abs;

public class Code implements Runnable {

    public static void main(String[] args) throws IOException {
        new Thread(new Code()).start();
    }

    private void solve() throws IOException {
        int n = nextInt();

        boolean[][] ff = new boolean[2001][2001];
        Pair<Integer, Integer>[] coords = new Pair[n];
        for(int i = 0; i < n; ++i) {
            coords[i] = new Pair<Integer, Integer>(nextInt(), nextInt());
            ff[coords[i].first + 1000][coords[i].second + 1000] = true;
        }

        int ans = 0;
        double eps = 1e-8;
        Arrays.sort(coords);
        for(int i = 0; i + 2 < coords.length; ++i) {
            for(int j = i + 2; j < coords.length; ++j) {
                double centerx = (coords[j].first - coords[i].first) / 2.0 + coords[i].first;
                double centery = (coords[j].second - coords[i].second) / 2.0 + coords[i].second;
                int centerx2 = (coords[j].first - coords[i].first) / 2 + coords[i].first;
                int centery2 = (coords[j].second - coords[i].second) / 2 + coords[i].second;
                if(abs(centerx - centerx2) > eps || abs(centery - centery2) > eps)    continue;

                if(ff[centerx2 + 1000][centery2 + 1000])  ++ans;
            }
        }

        writer.println(ans);
    }

    private class Pair<E extends Comparable, V extends Comparable> implements Comparable<Pair<E, V>> {
        public Pair(E first, V second) {
            this.first = first;
            this.second = second;
        }

        @Override
        public int compareTo(Pair<E, V> obj) {
            if(first == obj.first)  return second.compareTo(obj.second);
            return first.compareTo(obj.first);
        }

        @Override
        public boolean equals(Object obj) {
            Pair other = (Pair)obj;
            return first.equals(other.first) && second.equals(other.second);
        }

        public E first;
        public V second;
    }

    @Override
    public void run() {
        try {
            if(in.equals(""))   reader = new BufferedReader(new InputStreamReader(System.in));
            else    reader = new BufferedReader(new FileReader(in));

            if(out.equals(""))  writer = new PrintWriter(new OutputStreamWriter(System.out));
            else    writer = new PrintWriter(new FileWriter(out));
            solve();
        } catch(IOException e) {
            e.printStackTrace();
        } finally {
            try {
                reader.close();
                writer.close();
            } catch(IOException e) {
                e.printStackTrace();
            }
        }
    }

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

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

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

    private float nextFloat() throws IOException {
        return Float.parseFloat(nextToken());
    }

    private String nextToken() throws IOException {
        while(st == null || !st.hasMoreTokens())    st = new StringTokenizer(reader.readLine());
        return st.nextToken();
    }

    private String in = "", out = "";
    private BufferedReader reader;
    private PrintWriter writer;
    private StringTokenizer st;
}