#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int n, m;
  cin >> n >> m;
  vector<pair<int, int>> v(m);
  rep(i, m) cin >> v[i].first >> v[i].second;
  sort(v.begin(), v.end(), [](auto x, auto y) {
    return tie(x.second, x.first) < tie(y.second, y.first);
  });
  int ans = n;
  int cur = 0;
  rep(i, m) {
    if (v[i].first > cur) ans--, cur = v[i].second;
  }
  cout << ans << '\n';
  return 0;
}