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

struct BST {
	struct Node {
		int key;
		int val;
		int min_key = key;
		int max_key = key;
		int max_val = val;
		int size = 1;
		int height = 1;
		Node* left = nullptr;
		Node* right = nullptr;

		static int get_min_key(Node* node) {
			if (node == nullptr) {
				return INT_MAX;
			}
			return node->min_key;
		}

		static int get_max_key(Node* node) {
			if (node == nullptr) {
				return INT_MIN;
			}
			return node->max_key;
		}

		static int get_max_val(Node* node) {
			if (node == nullptr) {
				return INT_MIN;
			}
			return node->max_val;
		}

		static int get_size(Node* node) {
			if (node == nullptr) {
				return 0;
			}
			return node->size;
		}

		static int get_height(Node* node) {
			if (node == nullptr) {
				return 0;
			}
			return node->height;
		}

		static void update(Node* node) {
			node->min_key = min(node->key, min(get_min_key(node->left), get_min_key(node->right)));
			node->max_key = max(node->key, max(get_max_key(node->left), get_max_key(node->right)));
			node->max_val = max(node->val, max(get_max_val(node->left), get_max_val(node->right)));
			node->size = 1 + get_size(node->left) + get_size(node->right);
			node->height = 1 + max(get_height(node->left), get_height(node->right));
		}

		static void rotate_left(Node*& node) {
			Node* temp = node->right;
			node->right = temp->left;
			temp->left = node;
			node = temp;
		}

		static void rotate_right(Node*& node) {
			Node* temp = node->left;
			node->left = temp->right;
			temp->right = node;
			node = temp;
		}

		static bool insert(Node*& node, int key, int val) {
			if (node == nullptr) {
				node = new Node(key, val);
				return true;
			}
			bool inserted;
			if (key < node->key) {
				inserted = insert(node->left, key, val);
			}
			else if (key > node->key) {
				inserted = insert(node->right, key, val);
			}
			else {
				inserted = false;
			}
			if (inserted) {
				int hl = get_height(node->left);
				int hr = get_height(node->right);
				if (hr - hl > 1) {
					rotate_left(node);
					update(node->left);
				}
				else if (hl - hr > 1) {
					rotate_right(node);
					update(node->right);
				}
				update(node);
			}
			return inserted;
		}

		static Node* lower_bound(Node* node, int key) {
			Node* result = nullptr;
			while (node != nullptr) {
				if (node->key >= key) {
					result = node;
					node = node->left;
				} else {
					node = node->right;
				}
			}
			return result;
		}

		static Node* upper_bound(Node* node, int key) {
			Node* result = nullptr;
			while (node != nullptr) {
				if (node->key > key) {
					result = node;
					node = node->left;
				} else {
					node = node->right;
				}
			}
			return result;
		}

		static int range_max(Node* node, int l, int h) {
			if (node == nullptr) {
				return INT_MIN;
			}
			if (node->max_key < l || node->min_key > h) {
				return INT_MIN;
			}
			if (node->min_key >= l && node->max_key <= h) {
				return node->max_val;
			}
			int result = max(range_max(node->left, l, h), range_max(node->right, l, h));
			if (node->key >= l && node->key <= h) {
				result = max(result, node->val);
			}
			return result;
		}
	};

	Node* root = nullptr;

	bool insert(int key, int val) {
		return Node::insert(root, key, val);
	}

	Node* lower_bound(int key) {
		return Node::lower_bound(root, key);
	}

	Node* upper_bound(int key) {
		return Node::upper_bound(root, key);
	}

	int range_max(int min_key, int max_key) {
		return Node::range_max(root, min_key, max_key);
	}
};

BST s[4000005];

void insert(int i,int l,int r,int x,int y,int v){
	if(l>x||r<x){
		return;
	}
	s[i].insert(y,v);
	if(l==r){
		return;
	}
	insert(i*2+1,l,(l+r)/2,x,y,v);
	insert(i*2+2,(l+r)/2+1,r,x,y,v);
}

int query_max(int i,int l,int r,int x0,int y0,int x1,int y1){
	if(l>x1||r<x0){
		return 0;
	}
	if(l>=x0&&r<=x1){
		return s[i].range_max(y0,y1);
	}
	int ans1=query_max(i*2+1,l,(l+r)/2,x0,y0,x1,y1);
	int ans2=query_max(i*2+2,(l+r)/2+1,r,x0,y0,x1,y1);
	return max(ans1,ans2);
}

signed main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
#ifdef CB
	freopen("be2.txt","r",stdin);
//	freopen("out.txt","w",stdout);
#endif
	int N;
	cin>>N;
	vector<int>r(N),a(N);
	for(int i=0;i<N;i++){
		cin>>r[i]>>a[i];
	}
	int ans=0;
	for(int i=0;i<N;i++){
		int v=query_max(0,1,1000000,1,1,r[i]-1,a[i]-1)+1;
		insert(0,1,1000000,r[i],a[i],v);
		ans=max(ans,v);
	}
	cout<<ans<<'\n';
	return 0;
}