#include<bits/stdc++.h>
using namespace std;
const int N=200010;
int n,m;
int l,r;
int ans;
pair<int,int> g[N];
int main()
{
    freopen("bridge.in","r",stdin);
    freopen("bridge.out","w",stdout);
    scanf("%d%d",&n,&m);
    for(int i=1;i<=m;i++)
        scanf("%d%d",&g[i].first,&g[i].second);
    sort(g+1,g+1+m);
    for(int i=1;i<=m;i++)
    {
        if(g[i].first>=r) ans++,l=g[i].first,r=g[i].second;
        else l=g[i].first,r=min(r,g[i].second);
    }
    printf("%d",ans);
    return 0;
}