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();
        Unit[] units = new Unit[m];
        for (int i = 0; i < m; i++) {
            units[i] = new Unit(sc.nextInt(), sc.nextInt());
        }
        Arrays.sort(units);
        int prev = 0;
        int count = 0;
        for (Unit x : units) {
            if (prev < x.left) {
                count++;
                prev = x.right;
            }
        }
        System.out.println(n - count);
    }
    
    static class Unit implements Comparable<Unit> {
        int left;
        int right;
        
        public Unit(int left, int right) {
            this.left = left;
            this.right = right;
        }
        
        public int compareTo(Unit another) {
            return right - another.right;
        }
    }
}
    
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    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();
    }
    
}