#include "bits/stdc++.h"
//#include "atcoder/all"
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
//const long long LINF = 1e18;
//const bool debug = false;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n-1); i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define endl "\n"
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
bool comp(const P& lh, const P& rh) { return lh.second < rh.second; }
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n, m; cin >> n >> m;
	vector<P>a(m);
	rep(i, m)cin >> a[i].first >> a[i].second;
	sort(all(a), comp);
	int ans = n;
	int now = -1;
	rep(i, m) {
		if (now < a[i].first) {
			now = a[i].second;
			ans--;
		}
	}
	cout << ans << endl;
	return 0;
}