1 #include<iostream>
2 using namespace std;
3
4 #include<vector>
5 #include<math.h>
6 #include<iomanip>
7 #include<string.h>
8
9 void swap(int &a,int &b)
10 {
11 int c = a;
12 a = b;
13 b = c;
14 }
15
16 int partition(vector<int> &vs,vector<int> &ve,int start,int end)
17 {
18 int a = vs[start];
19 int b = ve[start];
20 while(start < end)
21 {
22 while(start < end && vs[end] >= a) --end;
23 if(start < end)
24 {
25 vs[start] = vs[end];
26 ve[start] = ve[end];
27 }
28 while(start < end && vs[start] <= a) ++start;
29 if(start < end)
30 {
31 vs[end] = vs[start];
32 ve[end] = ve[start];
33 }
34 }
35 vs[start] = a;
36 ve[start] = b;
37 return start;
38 }
39
40 void quickSort(vector<int> &vs,vector<int> &ve,int start,int end)
41 {
42 if(start < end)
43 {
44 int pos = partition(vs,ve,start,end);
45 quickSort(vs,ve,start,pos-1);
46 quickSort(vs,ve,pos+1,end);
47 }
48 }
49
50 int max(int count[],int start,int end)
51 {
52 int c = count[start];
53 for(int i = start+1;i < end;i++)
54 {
55 if(c < count[i]) c = count[i];
56 }
57 return c;
58 }
59
60 int findFirst(vector<int> vs,int a,int end)
61 {
62 int i = 0;
63 while(vs[i] < a && i <= end) i++;
64 if(i > end) return -1;
65 return i;
66 }
67
68 int main()
69 {
70 int n,s,e,c,maxcount;
71 while(cin>>n && n != 0)
72 {
73 c = 0;
74 int count[n],i;
75 memset(count,0,sizeof(int)*n);
76 vector<int> vs,ve;
77 for(i = 0;i < n;i++)
78 {
79 cin>>s>>e;
80 vs.push_back(s);
81 ve.push_back(e);
82 }
83 quickSort(vs,ve,0,vs.size()-1);
84 for(i = 1;i < vs.size();)
85 {
86 while(vs[i] == vs[i-1])
87 {
88 ++c;
89 ++i;
90 }
91 quickSort(ve,vs,i-c-1,i-1);
92 c = 0;
93 ++i;
94 }
95 i = vs.size()-1;
96 while(vs[i] == vs[i-1])
97 {
98 count[i] = 1;
99 --i;
100 }
101 count[i] = 1;
102 --i;
103 maxcount = 1;
104 for(;i >= 0;--i)
105 {
106 int start = findFirst(vs,ve[i],vs.size()-1);
107 if(start == -1)
108 {
109 count[i] = 1;
110 continue;
111 }
112 count[i] = 1+max(count,start,vs.size()-1);
113 if(maxcount < count[i]) maxcount = count[i];
114 }
115
116 cout<<maxcount<<endl;
117 }
118
119 return 0;
120 }
