8pts求条

#include<bits/stdc++.h>
using namespace std;
struct node
{
	int x;
	int y;
}a[50005];
bool cmp(node x,node y)
{
	return x.x>x.y;
}
int cnt;
int ans;
int main()
{
	int n;
	cin>>n;
	for (int i=1;i<=n;i++)
	{
		cin>>a[i].x>>a[i].y;
	}
	sort(a+1,a+n+1,cmp);
	for (int i=1;i<=n;i++)
	{
		if (a[i].x>=cnt)
		{
			ans++;
			cnt=a[i].y;
		}
	}
	cout<<ans<<endl;
	
	return 0;
}