1 #include<cstdio>
 2 #include<cstring>
 3 #include<algorithm>
 4 using namespace std;
 5 
 6 struct as
 7 {
 8     int begin;
 9     int end;
10     
11  } aa[104];
12  
13  bool cmp(as x,as y)
14  {
15      return x.end<y.end;//结束时间排序
16  }
17  int main()
18  {
19           int N,i;
20           while(scanf("%d",&N),N)
21           {
22               
23           
24               for(i=0;i<N;i++)
25                   scanf("%d%d",&aa[i].begin,&aa[i].end);
26                sort(aa,aa+N,cmp);
27                int cot=1,tim=aa[0].end;//排在第一个，肯定要选
28                for(i=1;i<N;i++)
29                {
30                        if(aa[i].begin>=tim)
31                        {
32                        tim=aa[i].end;
33                        cot++;
34                     }
35                }
36                printf("%d\n",cot);
37            }
38 }
39