C++ :

#include<bits/stdc++.h>
using namespace std;
int n,ans;
struct point 
{
	int x,y;
}a[1000005];
int read()
{
	int num;
	char ch;
	while((ch=getchar())<'0'||ch>'9');
	num=ch-'0';
	while((ch=getchar())>='0'&&ch<='9')
	  num=num*10+ch-'0';
	return num;
}
bool  cmp(point a,point b)
{
	return a.y<b.y;
}
int main()
{
	n=read();
	for(int i=1;i<=n;i++)
	{
		a[i].x=read();
		a[i].y=read();
	}
	sort(a+1,a+1+n,cmp);
	int bj=0;
	for(int i=1;i<=n;i++)
	  if(bj<=a[i].x)
		{
			bj=a[i].y;
			ans++;
		}
	printf("%d",ans);
	return 0; 
}