#include <bits/stdc++.h>

using namespace std;

#define REP(i,n) for(int i=0; i<(int)(n); i++)

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  int n;
  cin >> n;
  vector<long long> x(n), y(n);
  
  REP (i, n)
    cin >> x[i] >> y[i];

  vector<tuple<long long, int, int> > dist;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < i; j++) {
      long long dx = x[i] - x[j];
      long long dy = y[i] - y[j];
      dist.emplace_back(dx * dx + dy * dy, i, j);
    }
  }

  vector<bool> vis(n);
  sort(dist.begin(), dist.end());

  int ret = 0;
  for (auto &[d, i, j]: dist) {
    if (vis[i] || vis[j]) continue;
    if (i == 0) {
      ++ret;
      vis[j] = true;
    } else if (j == 0) {
      ++ret;
      vis[i] = true;
    } else {
      vis[i] = vis[j] = true;
    }
  }
  cout << ret << endl;
  
  return 0;
}