// Arup Guha
// Solution to Decmber 2014 USACO Bronze Problem: Cow Jog

import java.util.*;
import java.io.*;
public class cowjog {

	public static void main(String[] args) throws Exception {

		Scanner fin = new Scanner(new File("cowjog.in"));
		PrintWriter fout = new PrintWriter("cowjog.out");

		// Read in data into cow objects.
		int n = fin.nextInt();
		cow[] myCows = new cow[n];
		for (int i=0; i<n; i++) {
			int pos = fin.nextInt();
			int speed = fin.nextInt();
			myCows[i] = new cow(pos, speed);
		}

		// This is key.
		Arrays.sort(myCows);

		// Go through cows in this order, they get a group if they're
		// position is after the LAST cow that has a group.
		int cnt = 0, curPos = -1;
		for (int i=0; i<n; i++) {
			if (myCows[i].pos > curPos) {
				cnt++;
				curPos = myCows[i].pos;
			}
		}

		// Print the result.
		fout.print(cnt);
		fin.close();
		fout.close();
	}
}

class cow implements Comparable<cow> {

	public int pos;
	public int speed;

	public cow(int start, int velocity) {
		pos = start;
		speed = velocity;
	}

	// Slower cows go first, then break ties by current position.
	public int compareTo(cow other) {
		if (this.speed != other.speed) return this.speed-other.speed;
		return this.pos - other.pos;
	}
}