> //E
> #include <stdio.h>
> #include <memory.h>
> #include <algorithm>
> using namespace std;
> #define N 10000
> int dis[N],price[N];
> int myindex[N];
> bool cmp(int a,int b)
> {
> 	return dis[a]<dis[b]||(dis[a]==dis[b]&&price[a]<price[b]);
> }
> int solve(int n)
> {
> 	int i,pre=100000000,re=0;
> 	for ( i=0;i<n;i++ )myindex[i]=i;
> 	sort(myindex,myindex+n,cmp);
> 	for ( i=0;i<n;i++ )
> 	{
> 		if ( price[myindex[i]]<pre)
> 		{
> 			pre=price[myindex[i]];
> 			re++;
> 		}
> 	}
> 	return re;
> }
> int main()
> {
> 	int n,i;
> 	while ( scanf("%d",&n),n )
> 	{
> 		for ( i=0;i<n;i++ )scanf("%d %d",dis+i,price+i);
> 		printf("%d\n",solve(n));
> 	}
> 	return 0;
> }