#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
struct node
{
    int s,e;
}a[200];
bool cmp(node a,node b)
{
     return a.e<b.e;
}
int main()
{
    int n,i,ans;
    while(~scanf("%d",&n)&&n)
    {
      for(i=0;i<n;i++)
        scanf("%d%d",&a[i].s,&a[i].e);
        sort(a,a+n,cmp);
        ans=1;
        int f=a[0].e;
        for(i=1;i<n;i++)
        {
           if(a[i].s>=f)
              {
                 ans++;
                 f=a[i].e;
              }
        }
       printf("%d\n",ans);
    }
    return 0;
}