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

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int m = sc.nextInt();
        int q = sc.nextInt();
        Person[] persons = new Person[q + 1];
        persons[0] = new Person(0, 0);
        ArrayList<ArrayList<Integer>> dp = new ArrayList<>();
        dp.add(new ArrayList<>());
        dp.get(0).add(0);
        for (int i = 1; i <= q; i++) {
            persons[i] = new Person(sc.nextInt(), sc.nextInt());
            for (int j = dp.size() - 1; j >= 0; j--) {
                boolean ok = false;
                for (int x : dp.get(j)) {
                    if (persons[x].enable(persons[i])) {
                        if (j == dp.size() - 1) {
                            dp.add(new ArrayList<>());
                        }
                        dp.get(j + 1).add(i);
                        ok = true;
                        break;
                    }
                }
                if (ok) {
                    break;
                }
            }
        }
        System.out.println(dp.size() - 1);
    }
    
    static class Person {
        int left;
        int right;
        
        public Person(int left, int right) {
            this.left = left;
            this.right = right;
        }
        
        public boolean enable(Person another) {
            return left < another.left && 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 nextLine() throws Exception {
        return br.readLine();
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}