import java.util.PriorityQueue;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[] x = new int[n];
		int[] y = new int[n];
		for (int i = 0; i < n; i++) {
			x[i] = sc.nextInt();
			y[i] = sc.nextInt();
		}
		sc.close();

		PriorityQueue<Obj> que = new PriorityQueue<>((o1, o2) -> Long.compare(o1.d, o2.d));
		for (int i = 0; i < n; i++) {
			for (int j = i + 1; j < n; j++) {
				Obj o = new Obj();
				o.a = i;
				o.b = j;
				long dx = x[i] - x[j];
				long dy = y[i] - y[j];
				o.d = dx * dx + dy * dy;
				que.add(o);
			}
		}

		int ans = 0;
		boolean[] used = new boolean[n];
		while (!que.isEmpty()) {
			Obj o = que.poll();
			if (used[o.a] || used[o.b]) {
				continue;
			}
			if (o.a != 0 && o.b != 0) {
				used[o.a] = true;
				used[o.b] = true;
			} else {
				int c = o.a;
				if (c == 0) {
					c = o.b;
				}
				used[c] = true;
				ans++;
			}
		}
		System.out.println(ans);
	}

	static class Obj {
		int a, b;
		long d;
	}
}