1 #include <bits/stdc++.h>
2 using namespace std;
3
4 #define pb push_back
5 #define maxSize 3939
6 #define _for(i,a,b) for(int i = (a);i < (b);i ++)
7
8 struct s
9 {
10 int op;
11 int ed;
12 };
13
14 bool cmp(s s1,s s2)
15 {
16 return s1.ed < s2.ed;
17 }
18
19 int main()
20 {
21 vector<s> list;
22 int num;
23 while(~scanf("%d",&num) && num!=0)
24 {
25 _for(i,0,num)
26 {
27 int a,b;
28 scanf("%d %d",&a,&b);
29 list.push_back(s{a,b});
30 }
31
32 sort(list.begin(),list.end(),cmp);
33
34 int cnt = 0;
35 cnt ++;
36 int overtime = list[0].ed;
37 _for(i,1,num)
38 {
39 if(list[i].op >= overtime)
40 {
41 cnt ++;
42 overtime = list[i].ed;
43 }
44 }
45 cout << cnt << endl;
46 list.clear();
47 }
48
49 return 0;
50 }
