#include <cstdio>
#include <algorithm>

struct Element {
	int l,r;
};
Element a[200005];

int main(){
	int n,m;
	scanf("%d%d",&n,&m);
	for(int i = 1; i <= m; i++){
		scanf("%d%d",&a[i].l,&a[i].r);
	}
	std::sort(a+1,a+1+m,[](Element& u, Element& v){
		return u.r < v.r;
	});
	int ans = 0;
	int p = 1;
	int right = 0;
	while(p<=n){
		int np = p;
		while(np<=n && a[np].l<=right) np++;
		if(np>n) break;
		ans++;
		right = a[np].r;
		p = np+1;
	}
	printf("%d\n",n-ans);
	return 0;
}