#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;

struct war {
	int l, r;
} a[N];

bool cmp(war x, war y) {
	return x.r < y.r;
}

int main() {
	int n, m;
	cin >> n >> m;
	for (int i = 0; i < m; ++i)
	cin >> a[i].l >> a[i].r;
	sort(a, a + m, cmp);
	int ans = 0;
	int last = -1;
	for (int i = 0; i < m; ++i) {
		if (last < a[i].l) {
			ans++;
			last = a[i].r - 1;
		}
	}
	cout << ans << endl;

	return 0;
}