import java.util.*;
import java.io.*;
 
public class Main {
    public static void main(String[] args) throws Exception {
        FastScanner sc = new FastScanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
        StringBuilder sb = new StringBuilder();
        int n = sc.nextInt();
        boolean[] bomb = new boolean[n];
        Balloon[] bl = new Balloon[n];
        for(int i = 0; i < n; i++){
            int x = sc.nextInt();
            int y = sc.nextInt();
            bl[i] = new Balloon(x,y);
        }
        ArrayList<Dist> dl = new ArrayList<>();
        for(int i = 0; i < n; i++){
            for(int j = i+1; j < n; j++){
                dl.add(new Dist(i,j,(long)(bl[i].x-bl[j].x)*(bl[i].x-bl[j].x) + (long)(bl[i].y-bl[j].y)*(bl[i].y-bl[j].y)));
            }
        }
        Collections.sort(dl);
        int ans = 0;
        for(Dist d : dl){
            //pw.println(d.i + " " + d.j + " " + d.dist);
            if(d.i != 0 && d.j != 0){
                if(!bomb[d.i] && !bomb[d.j]){
                    bomb[d.i] = true;
                    bomb[d.j] = true;
                }
            }else if(d.i == 0){
                if(!bomb[d.j]) ans++;
                bomb[d.j] = true;
            }else{
                if(!bomb[d.i]) ans++;
                bomb[d.i] = true;
            }
        }
        pw.println(ans);
        pw.flush();
    }

    static class GeekInteger {
        public static void save_sort(int[] array) {
            shuffle(array);
            Arrays.sort(array);
        }
 
        public static int[] shuffle(int[] array) {
            int n = array.length;
            Random random = new Random();
            for (int i = 0, j; i < n; i++) {
                j = i + random.nextInt(n - i);
                int randomElement = array[j];
                array[j] = array[i];
                array[i] = randomElement;
            }
            return array;
        }
 
    }
}

class Balloon{
    int x,y;
    public Balloon(int x, int y){
        this.x = x;
        this.y = y;
    }
}

class Dist implements Comparable<Dist>{
    int i,j;
    long dist;
    public Dist(int i, int j, long dist){
        this.i = i;
        this.j = j;
        this.dist = dist;
    }
    
    public int compareTo(Dist d){
        if(this.dist < d.dist){
            return -1;
        }else if(this.dist > d.dist){
            return 1;
        }else{
            return 0;
        }
    }
}
class FastScanner {
    private BufferedReader reader = null;
    private StringTokenizer tokenizer = null;
    public FastScanner(InputStream in) {
        reader = new BufferedReader(new InputStreamReader(in));
        tokenizer = null;
    }

    public String next() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }

    public String nextLine() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                return reader.readLine();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken("\n");
    }

    public long nextLong() {
        return Long.parseLong(next());
    }

    public int nextInt() {
        return Integer.parseInt(next());
    }

    public double nextDouble() {
         return Double.parseDouble(next());
    }
    
    public String[] nextArray(int n) {
        String[] a = new String[n];
        for (int i = 0; i < n; i++)
            a[i] = next();
        return a;
    }

    public int[] nextIntArray(int n) {
        int[] a = new int[n];
        for (int i = 0; i < n; i++)
            a[i] = nextInt();
        return a;
    }

    public long[] nextLongArray(int n) {
        long[] a = new long[n];
        for (int i = 0; i < n; i++)
            a[i] = nextLong();
        return a;
    } 
}