#include <bits/stdc++.h>
using namespace std;

int main() {
	long long N, M; cin >> N >> M;
	vector <pair<long long, long long>> LR(M);
	for (int i = 0; i < M; i++) cin >> LR[i].first >> LR[i].second;
	sort(LR.begin(), LR.end());
	long long min_ = 1LL << 60;
	long long count = 0;

	for (int i = 0; i < M; i++) {
		if (LR[i].first <= min_) {
			min_ = min(min_, LR[i].second);
		}
		else {
			min_ = 1LL << 60;
			count++;
			i--;
		}
	}

	if (min_ != 1LL << 60) count++;
	cout << N - count << endl;
}