#include<iostream>
#include<set>
#include<map>
using namespace std;
const int N = 1e3 + 5;

struct post{
	int x, y;
	int id = i;
}a[N];

int p[N << 15];
set<int>s;
map<int, int>m1;

void solve(){
	int n, m;
	cin >> n >> m;
	for(int i = 1; i <= m; i++) cin >> a[i].x >> a[i].y, a[i].id = i, s.insert(a[i].x), s.insert(a[i].y);
	int index = 0;
	for(auto it : s){
		m1[it] = ++index;
	}
	for(int i = 1; i <= m; i++) a[i].x  = m1[a[i].x], a[i].y = m1[a[i].y];
	for(int i = 1; i <= m; i++){
		for(int j = a[i].x; j <= a[i].y; j++){
			p[j] = i;
		}
	}
	set<int>ans;
	for(int i = 1; i <= 2 * n; i++){
		ans.insert(p[i]);
	}
	cout << (ans.size() - ans.count(0));
}

int main(){
	int t = 1;
	//cin >> t;
	while(t--){
		solve();
	}
	return 0;
}