#include <bits/stdc++.h>
using namespace std;

/*<DEBUG>*/
#define tem template <typename 
#define can_shift(_X_, ...) enable_if_t<sizeof test<_X_>(0) __VA_ARGS__ 8, debug&> operator<<(T i)
#define _op debug& operator<<
tem C > auto test(C *x) -> decltype(cerr << *x, 0LL);
tem C > char test(...);
tem C > struct itr{C begin, end; };
tem C > itr<C> get_range(C b, C e) { return itr<C>{b, e}; }
struct debug{
#ifdef _LOCAL
	~debug(){ cerr << endl; }
	tem T > can_shift(T, ==){ cerr << boolalpha << i; return *this; }
	tem T> can_shift(T, !=){ return *this << get_range(begin(i), end(i)); }
	tem T, typename U > _op (pair<T, U> i){ 
		return *this << "< " << i.first << " , " << i.second << " >"; }
	tem T> _op (itr<T> i){
		*this <<  "{ ";
		for(auto it = i.begin; it != i.end; it++){
			*this << " , " + (it==i.begin?2:0) << *it;
		}
		return *this << " }";
	}
#else
tem T> _op (const T&) { return *this; }
#endif 
};

tem T>
string _ARR_(T* arr, int sz){
	string ret = "{ " + to_string(arr[0]); 
	for(int i = 1; i < sz; i++) ret += " , " +  to_string(arr[i]);
	ret += " }"; return ret;
}

#define exp(...) " [ " << #__VA_ARGS__ << " : " << (__VA_ARGS__) << " ]"
/*</DEBUG>*/

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef unsigned int uint;
typedef pair<int, int> pii;
//mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

#define pb push_back
#define FAST ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define TC int __TC__; cin >> __TC__; while(__TC__--)
#define ar array

const int INF = 1e9 + 7;


map<int, map<int,int>> fen;

int get(int x, int y){
	int ans = 0;	
	for(int i = x; i >= 1; i-=i&-i){
		for(int j = y; j >= 1; j-=j&-j) ans = max(ans, fen[i][j]);
	}
	return ans;
}

void mod(int x, int y, int v){
	for(int i = x; i < INF; i += i &-i){
		for(int j = y; j < INF; j += j & -j) fen[i][j] = max(fen[i][j], v);
	}
	return;
}

int main()
{
	FAST;
	int n; cin >> n;

	int ans = 0;
	for(int i = 0; i < n; ++i){
		int x, y; cin >> x >> y;
		int cur = get(x, y)+1;
		ans = max(ans, cur);
		mod(x,y, cur);
	}

	cout << ans << '\n';

	return 0;
}