/* -*- coding: utf-8 -*-
 *
 * 1557.cc:  No.1557 Binary Variable - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_M = 200000;

/* typedef */

typedef pair<int,int> pii;

/* global variables */

pii lrs[MAX_M];

/* subroutines */

/* main */

int main() {
  int n, m;
  scanf("%d%d", &n, &m);

  for (int i = 0; i < m; i++)
    scanf("%d%d", &lrs[i].first, &lrs[i].second);
  sort(lrs, lrs + m);

  int c = 0, x = 0;
  for (int i = 0; i < m; i++) {
    int li = lrs[i].first, ri = lrs[i].second;
    if (x < li) c++, x = ri;
  }

  printf("%d\n", n - c);
  return 0;
}