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();
        int[] lefts = new int[m];
        int[] rights = new int[m];
        for (int i = 0; i < m; i++) {
            lefts[i] = sc.nextInt();
            rights[i] = sc.nextInt();
        }
        PriorityQueue<Integer> queue = new PriorityQueue<>((a, b) -> rights[a] == rights[b] ? lefts[a] - lefts[b] : rights[a] - rights[b]);
        for (int i = 0; i < m; i++) {
            queue.add(i);
        }
        int ans = n;
        int current = 0;
        while (queue.size() > 0) {
            int idx = queue.poll();
            if (lefts[idx] > current) {
                current = rights[idx];
                ans--;
            }
        }
        System.out.println(ans);
    }
}
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();
        }
    }
    
}