ABC103D.cpp

#include <stack>
#include <queue>
#include <cstdio>
#include <iostream>
#include <stdio.h>
#include <algorithm>
#include <math.h>
#include <string>
 
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
#define Rep(i,n0,n) for(int i=n0;i<n;i++)
#define Com(i,j,n) for(int i=0;i<n-1;i++)for(int j=i+1;j<n;j++)
#define INF (1<<29)

int main (){
	int NN,MM,tempa,tempb,temp;
	cin >> NN >> MM;
	pair<int,int> temppair;
	vector <pair< int , int > > cuts;
	rep(i,MM){
		cin >> tempa >> tempb;
		if(tempa>tempb)	{temp = tempa;tempa = tempb;tempb = temp;}
		cuts.push_back(make_pair(tempa,tempb));
	}
	sort(cuts.begin(),cuts.end());
	int ff = cuts[0].first;
	int fb = cuts[0].second;
	int ans = 1;
	rep(i,MM){
		if(cuts[i].first == ff)	continue;
		if ( fb <= cuts[i].first ){
			ff = cuts[i].first;
			fb = cuts[i].second;
			ans ++;
		}
		if( fb > cuts[i].second ){
			fb = cuts[i].second;
		}
	}
	cout << ans << endl;
	return 0;
}