#include<stdio.h>
#define N 50000
void main()
{
	int n,a[N],b[N],i,j,t,m=1;
	scanf("%d",&n);
	while(n)
	{
		for(i=0;i<n;i++)
			scanf("%d %d",&a[i],&b[i]);
	for(j=0;j<n-1;j++)
        for(i=0;i<n-1-j;i++)
		{
      if(a[i]>a[i+1])
	  {
         t=a[i];
          a[i]=a[i+1];
          a[i+1]=t;
		  t=b[i];
          b[i]=b[i+1];
          b[i+1]=t;
	  }
	  if(a[i]==a[i+1]&&b[i]>b[i+1])
	  {
		  t=a[i];
          a[i]=a[i+1];
          a[i+1]=t;
		  t=b[i];
          b[i]=b[i+1];
          b[i+1]=t;
	  }
		}
     for(i=n-1;i>=0;i--)
	 {
		 if(a[n-1]>=a[n-2]&&b[n-1]>=b[n-2])
		break;
         if(a[i]==a[i-1]&&b[i]<b[i-1])
               m++;
		 if(a[i]>a[i-1]&&b[i]<b[i-1])
			 m++;
	 }
	 printf("%d\n",m);
	 m=1;
	 scanf("%d",&n);
	}

}