1 #include <cstdio>
 2 #include <cstring>
 3 #include <iostream>
 4 #include <algorithm>
 5 using namespace std;
 6 #define MAX 101
 7 struct node
 8 {
 9     int begin;
10     int end;
11 };
12 struct node p[MAX];
13 int n;
14 bool cmp(struct node x,struct node y)
15 {
16     if(x.end==y.end) return x.begin<y.begin;
17     return x.end<y.end;
18 }
19 void init()
20 {
21     memset(p,0,sizeof(p));
22 }
23 void read()
24 {
25     int i;
26     for(i=0;i<n;i++)
27         scanf("%d %d",&p[i].begin,&p[i].end);
28     sort(p,p+n,cmp);
29 }
30 void cal()
31 {
32     int ans=1;
33     int end=p[0].end;
34     int i;
35     for(i=1;i<n;i++)
36     {
37         if(p[i].begin>=end)
38         {
39             end=p[i].end;
40             ans++;
41             //cout<<p[i].begin<<" "<<p[i].end<<endl;
42         }
43     }
44     printf("%d\n",ans);
45 }
46 void solve()
47 {
48     init();
49     read();
50     cal();
51 }
52 
53 int main()
54 {
55     while(scanf("%d",&n)!=EOF&&n)
56     {
57         solve();
58     }
59     return 0;
60 }