#include<bits/stdc++.h>
using namespace std;
#define int long long
int n,m,now,ans;
struct node{
	int l,r;
}a[1000005];
bool cmp(node a1,node a2){
	if(a1.r==a2.r){
		return a1.l>a2.l;
	}
	return a1.r<a2.r;
}
signed main(){
    freopen("bridge.in","r",stdin);
    freopen("bridge.out","w",stdout);
    ios::sync_with_stdio(false);
    cin.tie(0),cout.tie(0);
    cin>>n>>m;
    for(int i=1;i<=m;i++){
    	cin>>a[i].l>>a[i].r;
    }
    sort(a+1,a+m+1,cmp);
    for(int i=1;i<=m;i++){
    	if(now<a[i].l){
    		now=a[i].r-1;
    		ans++;
    	}
    }
    cout<<ans;
    return 0;
}