import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int m = sc.nextInt();
        PriorityQueue<Pair> pairs = new PriorityQueue<>();
        for (int i = 0; i < m; i++) {
            pairs.add(new Pair(sc.nextInt(), sc.nextInt()));
        }
        int idx = 0;
        while (pairs.size() > 0) {
            Pair p = pairs.poll();
            if (p.left > idx) {
                n--;
                idx = p.right;
            }
        }
        System.out.println(n);
    }
    
    static class Pair implements Comparable<Pair> {
        int left;
        int right;
        
        public Pair(int left, int right) {
            this.left = left;
            this.right = right;
        }
        
        public int compareTo(Pair another) {
            if (left == another.left) {
                return another.right - right;
            } else {
                return left - another.left;
            }
        }
    }
}


class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}