import java.io.*;
import java.util.*;
import java.util.stream.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        Point[] points = new Point[n];
        ArrayList<Distance> distances = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            points[i] = new Point(sc.nextInt(), sc.nextInt());
            for (int j = 0; j < i; j++) {
                distances.add(new Distance(j, i, points[i].getDistance(points[j])));
            }
        }
        Collections.sort(distances);
        int ans = 0;
        boolean[] used = new boolean[n];
        for (Distance x : distances) {
            if (x.left == 0) {
                if (!used[x.right]) {
                    used[x.right] = true;
                    ans++;
                }
            } else {
                if (!used[x.left] && !used[x.right]) {
                    used[x.left] = true;
                    used[x.right] = true;
                }
            }
        }
        System.out.println(ans);
    }
    
    static class Distance implements Comparable<Distance> {
        int left;
        int right;
        long value;
        
        public Distance(int left, int right, long value) {
            this.left = left;
            this.right = right;
            this.value = value;
        }
        
        public int compareTo(Distance another) {
            if (value == another.value) {
                return 0;
            } else if (value < another.value) {
                return -1;
            } else {
                return 1;
            }
        }
    }
    
    static class Point {
        long x;
        long y;
        
        public Point(long x, long y) {
            this.x = x;
            this.y = y;
        }
        
        public long getDistance(Point p) {
            return (x - p.x) * (x - p.x) + (y - p.y) * (y - p.y);
        }
    }
}
class Utilities {
    static String arrayToLineString(Object[] arr) {
        return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n"));
    }
    
    static String arrayToLineString(int[] arr) {
        return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new));
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public int[] nextIntArray() throws Exception {
        return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}