#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr ll LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 1000000007;
// constexpr int MOD = 998244353;
constexpr int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
constexpr int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  int n; cin >> n;
  vector<int> x(n), y(n); REP(i, n) cin >> x[i] >> y[i];
  auto d = [&](int i, int j) {
    return 1LL * (x[i] - x[j]) * (x[i] - x[j]) + 1LL * (y[i] - y[j]) * (y[i] - y[j]);
  };
  vector<pair<ll, pair<int, int>>> dist;
  REP(i, n) FOR(j, i + 1, n) dist.emplace_back(d(i, j), make_pair(i, j));
  sort(ALL(dist));
  vector<bool> b(n, true);
  int ans = 0;
  for (auto p : dist) {
    auto [x, y] = p.second;
    if (x == 0) {
      ans += b[y];
      b[y] = false;
    } else {
      if (b[x] && b[y]) b[x] = b[y] = false;
    }
  }
  cout << ans << '\n';
  return 0;
}