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();
	}
	
	boolean exist(int xs,int ys,int B,int x,int y,Set<Long> set) {
		for (int xnb=xs*B;xnb<(xs+1)*B;++xnb) {
			for (int ynb=ys*B;ynb<(ys+1)*B;++ynb) {
				int dx=x-xnb;
				int dy=y-ynb;
				if (dx*dx+dy*dy>=20*20) continue;
				if (set.contains((long)xnb<<32|ynb)) return true;
			}
		}
		return false;
	}

	void run() {
		FastScanner sc=new FastScanner();
		int N=sc.nextInt();
		int B=5;
		int MAX=(20000+B-1)/B;
		boolean[][] es=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) {
			int xs=X[i]/B;
			int ys=Y[i]/B;
			for (int dx=-4;dx<=4;++dx) {
				for (int dy=-4;dy<=4;++dy) {
					if (xs+dx<0||ys+dy<0||xs+dx>=MAX||ys+dy>=MAX) continue;
					if (!es[xs+dx][ys+dy]) continue;
					if (exist(xs+dx,ys+dy,B,X[i],Y[i],set)) {
						continue out;
					}
				}
			}
			set.add((long)X[i]<<32|Y[i]);
			es[xs][ys]=true;
			++ans;
		}
		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());}
}