#include <bits/stdc++.h>
using namespace std;
int n;
long long x, y;
int main() {
  std::ios_base::sync_with_stdio(false);
  cin >> n;
  vector<pair<long long, long long>> a(n);
  for (int i = 0; i < n; i++) {
    cin >> x >> y;
    a[i] = make_pair(x, y - x * x);
  }
  sort(a.begin(), a.end());
  if (n == 1) {
    cout << 0 << endl;
    return 0;
  }
  bool b[n];
  for (int i = 1; i < n; i++) {
    b[i - 1] = (a[i].first == a[i - 1].first);
  }
  b[n - 1] = false;
  stack<pair<long long, long long>> s;
  for (int i = 0; i < n; i++) {
    if (b[i]) continue;
    pair<long long, long long> p1, p2;
    while (s.size() > 1) {
      p2 = s.top();
      s.pop();
      p1 = s.top();
      if ((a[i].first - p2.first) * (p2.second - p1.second) -
              (a[i].second - p2.second) * (p2.first - p1.first) >
          0) {
        s.push(p2);
        break;
      }
    }
    s.push(a[i]);
  }
  cout << (s.size() - 1) << endl;
}
