#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, res = 0, a, b;
  cin >> n;
  vector<pair<long long, long long>> nums;
  for (int i = 0; i < n; i++) {
    cin >> a >> b;
    nums.push_back({a, b});
  }
  for (int i = 0; i < n; i++) {
    bool l = false, r = false, u = false, d = false;
    for (int j = 0; j < n; j++)
      if (i != j) {
        if (nums[j].second == nums[i].second && nums[j].first > nums[i].first)
          r = true;
        if (nums[j].second == nums[i].second && nums[j].first < nums[i].first)
          l = true;
        if (nums[j].second > nums[i].second && nums[j].first == nums[i].first)
          u = true;
        if (nums[j].second < nums[i].second && nums[j].first == nums[i].first)
          d = true;
      }
    res += (bool)(l && r && u && d);
  }
  cout << res;
  return 0;
}
