#include<algorithm>
#include<iostream>
#include<vector>
using namespace std;
typedef long long lint;
typedef vector<int>vi;
typedef pair<int,int>pii;
#define rep(i,n)for(int i=0;i<(int)(n);++i)

int main(){
  int n;
  cin>>n;
  vi l(n),r(n);
  rep(i,n)cin>>l[i]>>r[i];
  int ml=0;
  vector<int>m(n+1,1e7);
  rep(i,n){
    int p=0,f=ml+1;
    while(f-p>1){
      int x=(f+p)/2;
      int cur=m[x];
      if(max(l[i],cur+1)<=r[i]) p=x;
      else f=x;
    }
    ml=max(ml,p+1);
    //UPDATE
    m[p+1]=min(m[p+1],max(l[i],p==0?0:m[p]+1));
  }
  cout<<ml<<endl;
}