//LIS in any partially ordered domain
//https://www.quora.com/How-can-the-SPOJ-problem-LIS2-be-solved
//https://csit.am/2009/proceedings/2DMCA/5.pdf
//https://core.ac.uk/download/pdf/82062831.pdf
#include <iostream>
#include <map>
using namespace std;

struct NiceDay{
    map<int,int> M;
    bool find(int x, int y){
        map<int,int>::iterator lb = M.lower_bound(x);
        if (lb == M.begin())
            return false;
        lb--;
        if (lb->second < y)
            return true;
        else
            return false;
    }
    void add(int x, int y){
        map<int,int>::iterator lb = M.lower_bound(x);
        map<int,int>::iterator i2 = lb;
        while (i2 != M.end() && i2->second >= y)
            i2++;
        M.erase(lb,i2);
        M.insert(pair<int,int>(x,y));
    }
};
int main(){
    static NiceDay a[100010];
    int N, x, y;
    cin >> N >> x >> y;
    a[1].add(x,y);
    int L = 1;
    for(int i = 0; i < N-1; ++i){
        cin >> x >> y;
        int l = 0;
        int u = L;
        int m = 0;
        while(u > l){
            m = (l+u+1)/2;
            if(a[m].find(x,y))
                l = m;
            else
                u = m-1;
        }
        if (L <= l)
            L = l+1;
        a[l+1].add(x,y);
    }
    printf("%d\n", L);
}