import java.io.*;
import java.util.*;
import java.util.function.*;
import java.util.stream.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int m = sc.nextInt();
        PriorityQueue<Num> queue = new PriorityQueue<>();
        while (m-- > 0) {
            queue.add(new Num(sc.nextInt(), sc.nextInt()));
        }
        int current = 0;
        while (queue.size() > 0) {
            Num x = queue.poll();
            if (x.left > current) {
                current = x.right;
                n--;
            }
        }
        System.out.println(n);
    }
    
    static class  Num implements Comparable<Num> {
        int left;
        int right;
        
        public Num(int left, int right) {
            this.left = left;
            this.right = right;
        }
        
        public int compareTo(Num another) {
            return right - another.right;
        }
    }
}
class Scanner {
    BufferedReader br;
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() {
        try {
            br = new BufferedReader(new InputStreamReader(System.in));
        } catch (Exception e) {
            
        }
    }
    
    public int nextInt() {
        return Integer.parseInt(next());
    }
    
    public long nextLong() {
        return Long.parseLong(next());
    }
    
    public double nextDouble() {
        return Double.parseDouble(next());
    }
    
    public String next() {
        try {
            while (!st.hasMoreTokens()) {
                st = new StringTokenizer(br.readLine());
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            return st.nextToken();
        }
    }
    
}