#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
struct record
{
	int begin;
	int end;
}s[110];
bool cmp(record a,record b)
{
	if(a.end!=b.end)
	return a.end<b.end;
	else
	return a.begin>b.begin;
}
int main()
{
	int n,m,j,i,sum,k;
	int dp[11000];
	while(scanf("%d",&n)&&n!=0)
	{
		for(i=0;i<n;i++)
		scanf("%d%d",&s[i].begin,&s[i].end);
		sort(s,s+n,cmp);
		sum=1;
		k=s[0].end;
		for(i=1;i<n;i++)
		{
			if(k<=s[i].begin)
			{
				sum++;
				k=s[i].end;
			}
		}
		printf("%d\n",sum);
	}
	return 0;
}