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.InputStreamReader;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map.Entry;

public class B_181 {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		int n = Integer.parseInt(br.readLine());

		Edge[] edges = new Edge[n];

		for (int i = 0; i < n; i++) {
			String[] xy = br.readLine().split(" ");
			edges[i] = new Edge(Integer.parseInt(xy[0]), Integer.parseInt(xy[1]));
		}

		HashMap<String, Integer> hm = new HashMap<>();

		int count = 0;

		for (int i = 0; i < n - 1; i++) {
			for (int j = i + 1; j < n; j++) {
				double distance = distance(edges[i].x, edges[i].y, edges[j].x, edges[j].y);
				double m = (1.0 * (edges[i].y - edges[j].y) / (edges[i].x - edges[j].x));
				edges[i].add(m, distance);
				edges[j].add(m, distance);
			}
		}
		
		for (Edge edge : edges) {
			for (HashMap<Double, Integer> distanceMap: edge.hm.values()) {
				Collection<Integer> counting = distanceMap.values();
				
				count += counting.stream().reduce(0, Integer::sum) - counting.size();
			}
		}

		System.out.println(count);
	}

	static int getNoOfPoints(int totalLines) {
		return (int) Math.ceil(Math.sqrt(2 * totalLines));
	}
	
	static double distance(int x1, int y1, int x2, int y2) 
	{ 
	    return Math.sqrt(Math.pow(x2 - x1, 2) +  
	                Math.pow(y2 - y1, 2) * 1.0); 
	} 
}

class Edge {
	int x, y;

	HashMap<Double, HashMap<Double, Integer>> hm = new HashMap<>();

	Edge(int x, int y) {
		this.x = x;
		this.y = y;
	}

	public void add(Double slope, double distance) {
		if (this.hm.containsKey(slope)) {
			HashMap<Double, Integer> distanceAndCount = hm.get(slope);

			if (distanceAndCount.containsKey(distance)) {
				distanceAndCount.put(distance, distanceAndCount.get(distance) + 1);
			} else {
				distanceAndCount.put(distance, 1);
			}
			this.hm.put(slope, distanceAndCount);
		} else {
			HashMap<Double, Integer> distanceAndCount = new HashMap<>();
			distanceAndCount.put(distance, 1);
			this.hm.put(slope, distanceAndCount);
		}
	}
}
