import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.NoSuchElementException;
import java.util.Set;

public class Main {

	public static void main(String[] args) {
		new Main().run();
	}

	void run() {
		FastScanner sc=new FastScanner();
		ArrayList<Integer> x_circle=new ArrayList<>();
		ArrayList<Integer> y_circle=new ArrayList<>();
		for (int i=-20;i<=20;++i) {
			for (int j=-20;j<=20;++j) {
				if (i*i+j*j<20*20) {
					x_circle.add(i);
					y_circle.add(j);
				}
			}
		}
		int N=sc.nextInt();
		int MAX=(20000+13)/14;
		boolean[][] exist=new boolean[MAX][MAX];
		Set<Long> set=new HashSet<>();
		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();
		}
		
		int ans=0;
		out:for (int i=0;i<N;++i) {
			if (exist[X[i]/14][Y[i]/14]) continue;
			boolean empty=true;;
			out2:for (int dx=-2;dx<=2;++dx) {
				for (int dy=-2;dy<=2;++dy) {
					if (X[i]/14+dx<0||Y[i]/14+dy<0||X[i]/14+dx>=MAX||Y[i]/14+dy>=MAX) continue;
					empty &= !exist[X[i]/14+dx][Y[i]/14+dy];
					if (!empty) break out2;
				}
			}
			if (!empty) {
				for (int j=0;j<x_circle.size();++j) {
					long x=X[i]+x_circle.get(j);
					long y=Y[i]+y_circle.get(j);
					if (set.contains((long)x<<32|y)) {
						continue out;
					}
				}
			}
			++ans;
			set.add((long)X[i]<<32|Y[i]);
			exist[X[i]/14][Y[i]/14]=true;
		}
		System.out.println(ans);
	}
	
	void tr(Object...objects) {System.out.println(Arrays.deepToString(objects));}
}

class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        }else{
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }
    private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;}
    private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;}
    public boolean hasNext() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++; return hasNextByte();}
    public String next() {
        if (!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    public long nextLong() {
        if (!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while(true){
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
        return (int) nl;
    }
    
    public double nextDouble() { return Double.parseDouble(next());}
}