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

template <class A, class B> bool cmin(A& a, B b) { return a > b && (a = b, true); }
template <class A, class B> bool cmax(A& a, B b) { return a < b && (a = b, true); }

signed main() {
  cin.tie(nullptr)->sync_with_stdio(false);

  long N, M;
  cin >> N >> M;
  vector<pair<long, long>> V(N);
  for (long i = 0; i < N; i++) {
    long a, b;
    cin >> a >> b, a--, b--;
    V.at(i) = {a, b};
  }

  vector<set<long>> V2(M);
  for (const auto& [a, b] : V) V2.at(a).insert(b);

  long ans = 0;
  set<long> SE;
  for (const auto& se : V2) {
    bool b = 0;
    for (const auto& a : se) {
      if (SE.count(a)) {
        b = 1;
      } else {
        SE.insert(a);
      }
    }
    if (b) ans++;
  }
  cout << ans << '\n';
}