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.text.*; import java.io.BufferedReader;import java.math.*; import java.util.regex.*; import java.awt.geom.*; import static java.lang.Math.*; import static java.lang.Character.*; import static java.lang.Integer.*; import static java.lang.Double.*; import static java.lang.Long.*; import static java.lang.System.*; import static java.util.Arrays.*;

import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;

public class B {
    static BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    static PrintStream out = System.out;
    static int n;
    static int[][] a;
    static boolean[][] ok;
	static void readInput() throws IOException {
		n = new Integer(in.readLine());
		a = new int[n][];
		ok = new boolean[2012][2012];
		for (int i = 0; i < ok.length; i++)
			Arrays.fill(ok[i], false);
		
		for (int i = 0; i < n; i++) {
			a[i] = parseArrInt(in.readLine());
			ok[a[i][0]+1000] [a[i][1]+1000] = true;
		}
	}

	static void process() {
		int count = 0;
		for (int i = 0; i < n; i++) 
			for (int j = 0; j < n; j++) if (i!=j){
				int x = 2*a[i][0] - a[j][0];
				int y = 2*a[i][1] - a[j][1];
				if ((x+1000<2012) && (x+1000>=0) && (y+1000>=0)&& (y+1000 < 2012) && ok [x+1000][y+1000]) count++;
			}
		System.out.println(count/2);
	}

	public static void main(String[] args) throws IOException {
		readInput();
		process();
	}

	public static void debug(Object...os) { 
		System.err.println(Arrays.deepToString(os));
	} 
	static int[] parseArrInt(String s) {
		StringTokenizer st = new StringTokenizer(s);
		ArrayList<Integer> list = new ArrayList<Integer>();
		while (st.hasMoreTokens()) {
			list.add(Integer.parseInt(st.nextToken()));
		}
		Integer[] temp = list.toArray(new Integer[]{});
		int[] res = new int[temp.length];
		for (int i = 0; i < temp.length; i++) {
			res[i] = temp[i];
		}
		return (res);
	}

}
