import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Arrays;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String[] sa = br.readLine().split(" ");
		int n = Integer.parseInt(sa[0]);
		int m = Integer.parseInt(sa[1]);
		Obj[] arr = new Obj[m];
		for (int i = 0; i < m; i++) {
			sa = br.readLine().split(" ");
			Obj o = new Obj();
			o.l = Integer.parseInt(sa[0]);
			o.r = Integer.parseInt(sa[1]);
			arr[i] = o;
		}
		br.close();

		Arrays.sort(arr, (o1, o2) -> o1.r - o2.r);
		int cnt = 0;
		int x = 0;
		for (int i = 0; i < m; i++) {
			Obj o = arr[i];
			if (x < o.l) {
				x = o.r;
				cnt++;
			}
		}
		System.out.println(n - cnt);
	}

	static class Obj {
		int l, r;
	}
}