#include <bits/stdc++.h>
using namespace std;
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
template<int mod>istream &operator>>(istream &is,static_modint<mod> &a){long long b;is>>b;a=b;return is;}
istream &operator>>(istream &is,modint &a){long long b;cin>>b;a=b;return is;}
#endif
#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) static_cast<void>(0)
#define debugg(...) static_cast<void>(0)
#define esper(...) static_cast<void>(0)
template<typename T1,typename T2>ostream &operator<<(ostream &os,const pair<T1,T2>&p){os<<p.first<<' '<<p.second;return os;}
#endif
using ll=long long;
using ull=unsigned long long;
using P=pair<ll,ll>;
template<typename T>using minque=priority_queue<T,vector<T>,greater<T>>;
template<typename T>bool chmax(T &a,const T &b){return (a<b?(a=b,true):false);}
template<typename T>bool chmin(T &a,const T &b){return (a>b?(a=b,true):false);}
template<typename T1,typename T2>istream &operator>>(istream &is,pair<T1,T2>&p){is>>p.first>>p.second;return is;}
template<typename T>istream &operator>>(istream &is,vector<T> &a){for(auto &i:a)is>>i;return is;}
template<typename T1,typename T2>void operator++(pair<T1,T2>&a,int n){a.first++,a.second++;}
template<typename T1,typename T2>void operator--(pair<T1,T2>&a,int n){a.first--,a.second--;}
template<typename T>void operator++(vector<T>&a,int n){for(auto &i:a)i++;}
template<typename T>void operator--(vector<T>&a,int n){for(auto &i:a)i--;}
#define reps(i,a,n) for(int i=(a);i<int(n);i++)
#define rep(i,n) reps(i,0,n)
#define all(x) x.begin(),x.end()
#define pcnt(x) __builtin_popcountll(x)
#define fin(x) return cout<<x<<'\n',static_cast<void>(0)
ll myceil(ll a,ll b){return (a+b-1)/b;}
template<typename T,size_t n,size_t id=0>
auto vec(const int (&d)[n],const T &init=T()){
  if constexpr (id<n)return vector(d[id],vec<T,n,id+1>(d,init));
  else return init;
}
void SOLVE();
int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout<<fixed<<setprecision(16);
  #ifdef LOCAL
  clock_t start=clock();
  #endif
  int testcase=1;
  //cin>>testcase;
  for(int i=0;i<testcase;i++){
    SOLVE();
  }
  #ifdef LOCAL
  cerr<<"time:";
  cerr<<(clock()-start)/1000;
  cerr<<"ms\n";
  #endif
}
template<typename I,typename S,S (*op)(S,S),S (*e)()>
struct DynamicSegmentTree{
private:
  struct node{
    I id;
    S val,product;
    unique_ptr<node> left,right;
    node(I id,S val):id(id),val(val),product(val),left(nullptr),right(nullptr){}
    void update(){
      product=op(op(left?left->product:e(),val),right?right->product:e());
    }
  };
  unique_ptr<node> root;
  void set(unique_ptr<node>&t,I l,I r,I p,S x){
    if(!t){
      t=make_unique<node>(p,x);
      return;
    }
    if(t->id==p){
      t->val=x;
      t->update();
      return;
    }
    I nxt=(l+r)/2;
    if(p<nxt){
      if(t->id<p)swap(t->id,p),swap(t->val,x);
      set(t->left,l,nxt,p,x);
    }
    else{
      if(p<t->id)swap(t->id,p),swap(t->val,x);
      set(t->right,nxt,r,p,x);
    }
    t->update();
  }
  S get(const unique_ptr<node>&t,I l,I r,I p)const{
    if(!t)return e();
    if(t->id==p)return t->val;
    I nxt=(l+r)/2;
    if(p<nxt)return get(t->left,l,nxt,p);
    else return get(t->right,nxt,r,p);
  }
  S prod(const unique_ptr<node>&t,I a,I b,I l,I r)const{
    if(!t||b<=l||r<=a)return e();
    if(l<=a&&b<=r)return t->product;
    I nxt=(a+b)/2;
    S ret=prod(t->left,a,nxt,l,r);
    if(l<=t->id&&t->id<r)ret=op(ret,t->val);
    return op(ret,prod(t->right,nxt,b,l,r));
  }
  I L,R;
public:
  DynamicSegmentTree(I l,I r):L(l),R(r),root(nullptr){}
  void set(I p,S x){
    set(root,L,R,p,x);
  }
  S get(I p)const{
    return get(root,L,R,p);
  }
  S prod(I l,I r)const{
    return prod(root,L,R,l,r);
  }
  S all_prod()const{
    return root?root->product:e();
  }
};
int op(int x,int y){return max(x,y);}
int e(){return 0;}
void SOLVE(){
  int n;
  cin>>n;
  vector<pair<int,int>>a(n);
  cin>>a;
  sort(all(a),[](pair<int,int>x,pair<int,int>y){return x.second==y.second?x.first<y.first:x.second<y.second;});
  DynamicSegmentTree<int,int,op,e>seg(0,1e9+1000);
  rep(i,n){
    seg.set(a[i].first,seg.prod(a[i].first,1e9+1000)+1);
  }
  cout<<seg.all_prod()-1<<endl;
}