#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>

void findandreplace(std::vector<int>& v, int elem) {
  // Find the largest smallest
  int li = 0, lf = v.size() - 1;
  int sol = -1;
  while (li <= lf) {
    int m = (li + lf) / 2;
    if (v[m] <= elem) {
      sol = m;
      li = m + 1;
    } else {
      lf = m - 1;
    }
  }
  if (sol == -1) {
    std::cerr << "Bad times!" << std::endl;
    return;
  }
  v[sol] = elem;
}

int main()
{
  std::ifstream in("pachete.in");
  std::ofstream out("pachete.out");

  int n;
  std::vector<std::pair<int, int> > v;
  in >> n;
  for (int i = 0; i < n; ++i) {
    std::pair<int, int> p;
    in >> p.first >> p.second;
    v.push_back(p);
  }

  std::vector<int> h;

  std::sort(v.begin(), v.end());
  for (int i = 0; i < v.size(); ++i) {
    if (h.empty() || h[h.size() - 1] > v[i].second) {
      h.push_back(v[i].second);
    } else {
      findandreplace(h, v[i].second);
    }
  }

  out << h.size() << std::endl;

  in.close();
  out.close();

  return 0;
}