#include <bits/stdc++.h>
using namespace std;
int n,m,res=1;
struct node {
	int l,r;
}a[200010];
bool cmp (node x,node y) {
	return x.l<y.l;
}
int main () {
	freopen("bridge.in","r",stdin);
	freopen("bridge.out","w",stdout);
	cin >> n >> m;
	for (int i=1;i<=m;i++) {
		cin >> a[i].l >> a[i].r;
	} 
	sort(a+1,a+m+1,cmp);
	int L=a[1].l,R=a[1].r;
	for (int i=2;i<=m;i++) {
		if (a[i].l>=R) {
			res++;
			R=a[i].r;
			L=a[i].l;
		}else{
			L=a[i].l;
			R=min(R,a[i].r);
		}
	}
	cout << res <<endl;
	return 0;
}