package weblab;
import java.io.*;
import java.util.*;

class Job{
	int startTime;
	int endTime;

	public Job(int startTime, int endTime) {
		this.startTime=startTime;
		this.endTime=startTime+endTime;
	}
}
class Solution {

  // Implement the solve method to return the answer to the problem posed by the inputstream.
  public static String run(InputStream in) {
    return new Solution().solve(in);
  }

  public String solve(InputStream in) {
  Scanner scanner = new Scanner(in);
  int orders = scanner.nextInt();
  int noJobs = 0;
  List <Job>jobs = new ArrayList();


  while(scanner.hasNext()) {
	  jobs.add(new Job(scanner.nextInt(),scanner.nextInt()));
  }


  while(!jobs.isEmpty()) {
	noJobs++;
  Job firstDone= jobs.get(0);

  //get the job that's finished the earliest
  int i =0;
  for(Job job: jobs) {
	  if(job.endTime<firstDone.endTime) {
		  firstDone=jobs.get(i);
	  }
	  i++;
  }

  //remove job from available jobs
    jobs.remove(firstDone);
    if(jobs.size()==0) {
      return Integer.toString(noJobs);
    }
    Job firstReady= jobs.get(0);

  //List <Job>toBeRemoved = new ArrayList();
  remove(jobs,firstDone,firstReady);




  }
  return Integer.toString(noJobs);
  }

private void remove(List<Job> jobs, Job firstDone, Job firstReady) {
  int i =0;
	boolean next=false;

	//finds first available job
	for(Job job: jobs) {
		  if(job.startTime>=firstDone.endTime && job.endTime<firstReady.endTime) {
			  firstReady=jobs.get(i);
			  next=true;
		  }
		  i++;
	  }

	//  System.out.println("1");
	jobs.remove(firstReady);
	// System.out.println("2");
	if(next&&jobs.size()!=0) {

		remove(jobs,firstReady,jobs.get(0));
	}

}
}