#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<ll,ll> P;
typedef vector<ll> VI;
typedef vector<VI> VVI;
#define REP(i,n) for(ll i=0;i<(n);i++)
#define ALL(v) v.begin(),v.end()
template<typename T> bool chmax(T &x, const T &y) {return (x<y)?(x=y,true):false;};
template<typename T> bool chmin(T &x, const T &y) {return (x>y)?(x=y,true):false;};
constexpr ll MOD=998244353;
constexpr ll INF=2e18;

int main(){
    int n, m; cin >> n >> m;
    vector<P> p(m);
    REP(i,m) cin >> p[i].first >> p[i].second;
    sort(ALL(p));
    int ans=n;
    int r=-1;
    REP(i,m){
        if(r<p[i].first){
            ans--;
            r=p[i].second;
        }
    }
    cout << ans << endl;
    return 0;
}