#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using pll = pair<ll, ll>;
using tlll = tuple<ll, ll, ll>;
//constexpr ll MOD = 1e9 + 7;
constexpr ll MOD = 998244353;
//constexpr ll MOD = ;
ll mod(ll A, ll M) {return (A % M + M) % M;}
constexpr ll INF = 1LL << 60;
template<class T> bool chmin(T& a, T b) {if (a > b) {a = b; return true;} return false;}
template<class T> bool chmax(T& a, T b) {if (a < b) {a = b; return true;} return false;}
ll divceil(ll A, ll B) {return (A + (B - 1)) / B;}
#define FINALANS(A) do {cout << (A) << '\n'; exit(0);} while (false)

int main()
{
  ll N, M;
  cin >> N >> M;
  vector<pll> RL(M);
  for (ll i = 0; i < M; i++)
  {
    cin >> RL.at(i).second >> RL.at(i).first;
  }

  sort(RL.begin(), RL.end());

  ll r0 = 0;
  ll ans = N;
  for (ll i = 0; i < M; i++)
  {
    pll rl = RL.at(i);
    ll r = rl.first, l = rl.second;
    if (!(l <= r0 && r0 <= r))
    {
      r0 = r;
      ans--;
    }
  }
  cout << ans << endl;
}