#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(){
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  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);
  lint cc=0;
  bool ab=0;
  rep(i,n){
    if(cc>=1.3e9){ab=1;break;}
    int last=-1;
    for(int j=ml+1;j>=1;--j){
      int pre=j==1?0:m[j-1];
      if(m[j]<=l[i]){last=j;break;}
      if(pre+1<=r[i])m[j]=min(m[j],max(l[i],pre+1));
    }
    cc+=ml+1-last;
    if(m[ml+1]<1e7)ml++;
  }
  if(ab){
    ml=0;
    rep(i,n+1)m[i]=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;
}