import java.io.IOException;
import java.io.InputStream;
import java.util.HashSet;
import java.util.NoSuchElementException;
import java.util.Scanner;

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

	void run() {
		FastScanner sc = new FastScanner();
		int N = sc.nextInt();
		int[] X = new int[N];
		int[] Y = new int[N];
		int ans=0;
		HashSet[] set = new HashSet[20001];
		for (int i = 0; i < set.length; ++i)
			set[i] = new HashSet<Integer>();
		loop1: for (int i = 0; i < N; ++i) {
			X[i] = sc.nextInt();
			Y[i] = sc.nextInt();
			for (int x = -20 + X[i]; x <= 20 + X[i]; ++x) {
				for (int y = -20 + Y[i]; y <= 20 + Y[i]; ++y) {
					if ((x - X[i]) * (x - X[i]) + (y - Y[i]) * (y - Y[i]) >= 400)
						continue;
					if (x < 0 || y < 0 || x > 20000 || y > 20000)
						continue;
					if (set[x].contains(y)) {
						continue loop1;
					}
				}
			}
			set[X[i]].add(Y[i]);
			++ans;
		}
		System.out.println(ans);
	}

	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 boolean isPrintableChar(int c) {
			return 33 <= c && c <= 126;
		}

		private void skipUnprintable() {
			while (hasNextByte() && !isPrintableChar(buffer[ptr]))
				ptr++;
		}

		public boolean hasNext() {
			skipUnprintable();
			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() {
			return (int) nextLong();
		}
	}
}