#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000000

int main(){
	
	int N,M;
	cin>>N>>M;
	
	vector<pair<int,int>> X(M);
	rep(i,M){
		cin>>X[i].second>>X[i].first;
	}
	
	sort(X.begin(),X.end());
	
	int ans = N;
	int last = 0;
	rep(i,M){
		int R = X[i].first,L = X[i].second;
		if(L <= last)continue;
		ans--;
		last = R;
		
	}
	
	cout<<ans<<endl;
	
    return 0;
}