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.*;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Random;
import java.util.StringTokenizer;
import java.io.*;
import java.math.*;

public class CC
{
    static class pair implements Comparable<pair>
    {
        int x,y;
        pair(int x,int y){
            this.x=x;
            this.y=y;
        }
        public int compareTo(pair o)
        {
                return x-o.x;

        }
    }
    public static void main(String[] args) {

        StringBuffer sb = new StringBuffer();
        //int t=i();
        //while (t-->0)
        //{
          int n=i();
          int X[]=new int[n];
          int Y[]=new int[n];
        ArrayList<pair>A=new ArrayList<>();
          ArrayList<Integer>xx=new ArrayList<>();
        ArrayList<Integer>yy=new ArrayList<>();
          for(int i=0;i<n;i++)
          {
               X[i]=i();
               Y[i]=i();
               xx.add(X[i]);
               yy.add(Y[i]);
               A.add(new pair(X[i],Y[i]));

          }
          Collections.sort(A);
          int cnt=0;

            for(int i=0;i<n;i++)
          {
              int x1=X[i];
              int y1=Y[i];
              int u=0;
              for(int j=i+1;j<n;j++)
              {
                  int x2=X[j];
                  int y2=Y[j];
                  if((x1+x2)%2==0&& (y1+y2)%2==0)
                  {
                      int Mx=(x1+x2)/2;
                      int My=(y1+y2)/2;
                      pair s=new pair(Mx,My);
                              if(Collections.binarySearch(A,s)>0)
                                  cnt++;

                  }
              }
          }
            sb.append(cnt+"\n");














       // }






        System.out.println(sb.toString());
    }
//-------------------prime factorization********////////////////////////////////////
static TreeMap primefactorize(long n)
{
    TreeMap<Integer,Integer>h=new TreeMap<>();
    long number=n;
    for(int i=2;i<=Math.sqrt(n);i++)
    {
        if(n%i==0)
        {
            int cnt=0;
            while(n%i==0)
            {
                n=n/i;
                cnt++;
            }
            h.put(i,cnt);
        }
    }
    if(n!=1)
        h.put((int)n,1);
    return h;
}
///******************************SYSTEM PART*****************************************************************************************************************************************************************************************************************************************************////
    static InputReader in=new InputReader(System.in);
    static OutputWriter out=new OutputWriter(System.out);

    public static long pow(long a, long b)
    {
        long result=1;
        while(b>0){
            if (b % 2 != 0){
                result=(result*a);
                b--;
            }
            a=(a*a);
            b /= 2;
        }
        return result;
    }
    public static long gcd(long a, long b){
        if (a == 0){
            return b;
        }
        return gcd(b%a, a);
    }
    public static long lcm(long a, long b){
        return a*(b/gcd(a,b));
    }
    public static long l(){
        String s=in.String();
        return Long.parseLong(s);
    }
    public static void pln(String value){
        System.out.println(value);
    }
    public static int i(){
        return in.Int();
    }
    public static String s(){
        return in.String();
    }
}
///******************input Reader//***************************************************************************************************************************************************************************************
class InputReader
{
    private InputStream stream;
    private byte[] buf = new byte[1024];
    private int curChar;
    private int numChars;
    private SpaceCharFilter filter;
    public InputReader(InputStream stream) {
        this.stream = stream;
    }
    public int read() {
        if (numChars== -1)
            throw new InputMismatchException();
        if (curChar >= numChars) {
            curChar = 0;
            try {
                numChars = stream.read(buf);
            } catch (IOException e) {
                throw new InputMismatchException();
            }
            if (numChars <= 0)
                return -1;
        }
        return buf[curChar++];
    }
    public int Int() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = read();
        }
        int res = 0;
        do {
            if (c < '0' || c > '9')
                throw new InputMismatchException();
            res *= 10;
            res += c - '0';
            c = read();
        } while (!isSpaceChar(c));
        return res * sgn;
    }
    public String String() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        StringBuilder res = new StringBuilder();
        do {
            res.appendCodePoint(c);
            c = read();
        } while (!isSpaceChar(c));
        return res.toString();
    }
    public boolean isSpaceChar(int c) {
        if (filter != null)
            return filter.isSpaceChar(c);
        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }
    public String next() {
        return String();
    }
    public interface SpaceCharFilter
    {
        public boolean isSpaceChar(int ch);
    }
}

//*******************OUTPUT WRITER********************************************************************************************************************************************************************************************************************************************************//
class OutputWriter {
    private final PrintWriter writer;
    public OutputWriter(OutputStream outputStream) {
        writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
    }
    public OutputWriter(Writer writer) {
        this.writer = new PrintWriter(writer);
    }
    public void print(Object...objects) {
        for (int i = 0; i < objects.length; i++) {
            if (i != 0)
                writer.print(' ');
            writer.print(objects[i]);
        }
    }
    public void printLine(Object...objects) {
        print(objects);
        writer.println();
    }
    public void close() {
        writer.close();
    }
    public void flush() {
        writer.flush();
    }
}







