神奇题目，3=4

#include<bits/stdc++.h>
using namespace std;
struct ss{
	int s,e;
}a[114514];
bool cmp(ss aa,ss bb)
{
	return aa.e<bb.e;
}
int main()
{
	int n;
	cin>>n;
	for(int i=1;i<=n;i++)
		cin>>a[i].s>>a[i].e;
	sort(a+1,a+1+n,cmp);
	int ans=a[1].e;
	int cnt=1;
	for(int i=2;i<=n;i++)
	{
		if(ans<=a[i].s)
		{
			cnt++;
			ans=a[i].e;
		}
	}
	cout<<cnt;
}