180301_1931_회의실 배정

	//https://www.acmicpc.net/problem/1931 #include <iostream>
	#include <vector>
	#include <algorithm>
	using namespace std;
	#define lli long long int
	int main()
	{
	int n;
	cin >> n;
	vector<pair<lli, lli> > arr;
	for(int i=0; i<n; i++){
	int a, b;
	cin >> a >> b;
	arr.push_back(pair<lli, lli>(b,a));
	}
	sort(arr.begin(), arr.end());
	int cnt=1;
	int end=arr[0].first;
	for(int i=1; i<n; i++){
	if(end<=arr[i].second){
	end=arr[i].first;
	cnt++;
	}
	}
	cout << cnt << endl;
	return 0;
	}