#include <bits/stdc++.h>
using namespace std;
char string_in_buffer[(int)260];
void fast_scan(int &first) { scanf("%d", &first); }
void fast_scan(long long &first) { scanf("%lld", &first); }
void fast_scan(unsigned long long &first) { scanf("%llu", &first); }
void fast_scan(double &first) { scanf("%lf", &first); }
void fast_scan(long double &first) { scanf("%Lf", &first); }
void fast_scan(char &first) {
  scanf("%c", &first);
  if (first == '\n') {
    fast_scan(first);
  }
}
void fast_scan(string &first) {
  scanf("%s", string_in_buffer);
  first = string(string_in_buffer);
}
template <class TFirst, class TSecond>
void fast_scan(pair<TFirst, TSecond> &p) {
  fast_scan(p.first);
  fast_scan(p.second);
}
template <class T>
void fast_scan(vector<T> &v) {
  for (auto &first : v) fast_scan(first);
}
void fast_print(const int &first) { printf("%d", first); }
void fast_print(const unsigned int &first) { printf("%u", first); }
void fast_print(const long long &first) { printf("%lld", first); }
void fast_print(const unsigned long long &first) { printf("%llu", first); }
void fast_print(const double &first) { printf("%.15lf", first); }
void fast_print(const long double &first) { printf("%.15Lf", first); }
void fast_print(const char &first) { printf("%c", first); };
void fast_print(const string &first) { printf("%s", first.c_str()); }
void fast_print(const char v[]) { fast_print((string)v); }
template <class TFirst, class TSecond>
void fast_print(const pair<TFirst, TSecond> &p) {
  fast_print(p.first);
  fast_print(' ');
  fast_print(p.second);
}
template <class T>
void fast_print(const vector<T> &v) {
  if (v.empty()) return;
  fast_print(v[0]);
  for (int i = 1; i < v.size(); i++) {
    fast_print(' ');
    fast_print(v[i]);
  }
}
template <class T>
void fast_print(const vector<vector<T>> &v) {
  if (v.empty()) return;
  fast_print(v[0]);
  for (int i = 1; i < v.size(); i++) {
    fast_print('\n');
    fast_print(v[i]);
  }
}
template <class T>
void fast_print(const T &v) {
  for (const auto &first : v) {
    fast_print(first);
    fast_print(' ');
  }
}
using namespace std;
namespace smart_io {
string print_start = "";
string sep = " ";
bool first_print = false;
void precall_print() {
  fast_print(print_start);
  print_start = "\n";
  first_print = true;
}
void _print(deque<string>) {}
template <class T, class... Args>
void _print(deque<string> names, T elem, Args... args) {
  if (!first_print) {
    fast_print("\n");
  } else {
    first_print = false;
  }
  fast_print(names.front());
  fast_print(" = ");
  fast_print(elem);
  names.pop_front();
  _print(names, args...);
}
}  // namespace smart_io
template <class T>
ostream &operator,(ostream &os, const T &object) {
  if (!smart_io::first_print) {
    fast_print(smart_io::sep);
  } else {
    smart_io::first_print = false;
  }
  fast_print(object);
  return os;
}
template <class T>
istream &operator,(istream &is, T &object) {
  fast_scan(object);
  return is;
}
namespace escape__from__random__aetuhoetnuhshe {
using namespace std::chrono;
mt19937 rng(duration_cast<milliseconds>(system_clock::now().time_since_epoch())
                .count());
uniform_real_distribution<> prob_dist(0.0, 1.0);
};  // namespace escape__from__random__aetuhoetnuhshe
namespace typedefs {}
namespace numbers_operation {
template <class T>
T floor_mod(T a, T b) {
  if (a >= 0 && b >= 0) return a % b;
  if (a <= 0 && b <= 0) return a % b;
  return abs(b) - (abs(a) % abs(b));
}
}  // namespace numbers_operation
using namespace numbers_operation;
using namespace typedefs;
using namespace escape__from__random__aetuhoetnuhshe;
long long n;
vector<pair<long long, long long>> v;
long long operator^(pair<long long, long long> a,
                    pair<long long, long long> b) {
  return a.first * b.second - a.second * b.first;
}
pair<long long, long long> operator-(pair<long long, long long> a,
                                     pair<long long, long long> b) {
  return make_pair(a.first - b.first, a.second - b.second);
}
signed main() {
  cin, n;
  if (n == 1) {
    smart_io::precall_print();
    cout, 0;
    return 0;
  }
  v.resize(n);
  cin, v;
  for (long long i = 0; i < (n); i++) {
    v[i] = make_pair(v[i].first, v[i].second - v[i].first * v[i].first);
  }
  pair<long long, long long> down = v[0];
  for (long long i = 1; i < ((long long)v.size()); i++) {
    if (make_pair(v[i].second, v[i].first) <
        make_pair(down.second, down.first)) {
      down = v[i];
    }
  }
  vector<pair<long long, long long>> filt;
  for (pair<long long, long long> p : v)
    if (p != down)
      filt.emplace_back(p.first - down.first, p.second - down.second);
  v = filt;
  sort(v.begin(), v.end(),
       [](pair<long long, long long> a, pair<long long, long long> b) {
         if ((a ^ b) == 0) {
           return abs(a.first) + abs(a.second) < abs(b.first) + abs(b.second);
         } else {
           return (a ^ b) > 0;
         }
       });
  vector<pair<long long, long long>> st{make_pair(0, 0)};
  for (pair<long long, long long> p : v) {
    while (((long long)st.size()) >= 2) {
      pair<long long, long long> base = st[((long long)st.size()) - 2];
      pair<long long, long long> sub = st.back();
      if (((sub - base) ^ (p - base)) <= 0) {
        st.pop_back();
      } else {
        break;
      }
    }
    st.push_back(p);
  }
  long long cnt = 0;
  for (long long i = 0; i < ((long long)st.size()); i++) {
    long long j = (i + 1) % ((long long)st.size());
    if (st[i].first > st[j].first) cnt++;
  }
  smart_io::precall_print();
  cout, cnt;
}
