#include <bits/stdc++.h>
using namespace std; 
/* run this program using the console pauser or add your own getch, system("pause") or input loop */

int main(int argc, char** argv) 
{
	int n;
	cin>>n;
	int a[n]={};
	int b[n]={};
	for(int i=0;i<n;i++)
	{
		cin>>a[i]>>b[i];
	}
	sort(b,b+n);
	int p = 0;
	int ans=0;
	for(int i=0;i<n;i++)
	{
		if(p<=a[i])
		{
			p = b[i];
			ans++;
		}
	}
	cout<<ans;
	return 0;
}

本地样例过了