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

vector<set<array<int, 2>>> lis;

void add(array<int, 2> a, set<array<int, 2>>& s){
    s.insert(a);
    auto it = s.upper_bound(a);
    while(it != s.end()){
        if((*it)[1] >= a[1]) it = s.erase(it);
        else break;
    }
}

bool check(array<int, 2> a, set<array<int, 2>>& s){
    auto it = s.upper_bound({a[0], -1});
    if(it == s.begin()) return false;
    it--;
    return ((*it)[1] < a[1]);
}

void solve(array<int, 2> a){
    int lo = -1, hi = lis.size(), mid;
    while(lo + 1 < hi){
        mid = (lo + hi) / 2;
        if(check(a, lis[mid])) lo = mid;
        else hi = mid;
    }
    if(lo + 1 >= lis.size()) lis.push_back({});
    add(a, lis[lo + 1]);
}

int main() {
    int n;
    cin >> n;
    lis = {{{0, 0}}};
    for(int i = 0; i < n; i++){
        array<int, 2> a;
        cin >> a[0] >> a[1];
        solve(a);
    }
    cout << lis.size() - 1;
}