1 #include<cstdio>
2 #include<cstdlib>
3 #include<cmath>
4 #include<cstring>
5 #include<algorithm>
6 #include<iostream>
7 #include<vector>
8 #include<map>
9 #include<set>
10 #include<queue>
11 #include<string>
12 #define inf 1000000000
13 #define maxn 1000
14 #define maxm 500+100
15 #define eps 1e-10
16 #define ll long long
17 #define pa pair<int,int>
18 #define for0(i,n) for(int i=0;i<=(n);i++)
19 #define for1(i,n) for(int i=1;i<=(n);i++)
20 #define for2(i,x,y) for(int i=(x);i<=(y);i++)
21 #define for3(i,x,y) for(int i=(x);i>=(y);i--)
22 #define mod 1000000007
23 using namespace std;
24 inline int read()
25 {
26 int x=0,f=1;char ch=getchar();
27 while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
28 while(ch>=‘0‘&&ch<=‘9‘){x=10*x+ch-‘0‘;ch=getchar();}
29 return x*f;
30 }
31 int now[2],n,ans;
32 struct rec{int x,y;}a[maxn];
33 inline bool cmp(rec a,rec b)
34 {
35 return a.y<b.y;
36 }
37 int main()
38 {
39 freopen("input.txt","r",stdin);
40 freopen("output.txt","w",stdout);
41 n=read();
42 for1(i,n)a[i].x=read(),a[i].y=read();
43 sort(a+1,a+n+1,cmp);
44 now[0]=now[1]=0;
45 for1(i,n)
46 {
47 if(a[i].x>=now[1])ans++,now[1]=a[i].y;
48 else if(a[i].x>=now[0])ans++,now[0]=a[i].y;
49 if(now[0]>now[1])swap(now[0],now[1]);
50 }
51 printf("%d\n",ans);
52 return 0;
53 }
