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();
        Pair[] pairs = new Pair[m];
        for (int i = 0; i < m; i++) {
            pairs[i] = new Pair(sc.nextInt(), sc.nextInt());
        }
        Arrays.sort(pairs);
        int max = 0;
        for (Pair x : pairs) {
            if (x.left > max) {
                max = x.right;
                n--;
            }
        }
        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 (right == another.right) {
                return left - another.left;
            } else {
                
                return right - another.right;
            }
        }
    }
}

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 double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}