//简单....
 1 #include<iostream>

 #include<cstdio>

 #include<cstdlib>

 using namespace std;

 #define maxn 105

 struct t

 {

     int s;

     int e;

 };

 t T[maxn];

 int cmp(const void *_p,const void *_q)

 {

     t *p = (t *)_p;

     t *q = (t *)_q;

     return p->e - q->e;

 }

 int n;

 int main()

 {

     int res;

     int cur;

     while(scanf("%d",&n) && n)

     {

         for(int i = ; i < n; i++)

             scanf("%d%d",&T[i].s,&T[i].e);

         qsort(T,n,sizeof T[],cmp);

         cur = T[].e;

         res = ;

         for(int i = ; i < n; i++)

         {

             if(T[i].s >= cur)

             {

                 cur = T[i].e;

                 res++;

             }

         }

         printf("%d\n",res);

     }

     return ;

 }