#include <bits/stdc++.h>
const int maxn = 1e5 + 100;
const double pi = 2 * acos(0.0);
using namespace std;
struct Point {
  double x, y;
  Point() {}
  Point(double a, double b) { x = a, y = b; }
} p[maxn], st[maxn];
const double eps = 1e-10;
Point operator+(Point A, Point B) { return Point(A.x + B.x, A.y + B.y); }
Point operator-(Point A, Point B) { return Point(A.x - B.x, A.y - B.y); }
Point operator*(Point A, double p) { return Point(A.x * p, A.y * p); }
Point operator/(Point A, double p) { return Point(A.x / p, A.y / p); }
bool operator<(const Point &a, const Point &b) {
  return a.x < b.x || (a.x == b.x && a.y < b.y);
}
int dcmp(double x) {
  if (fabs(x) < eps)
    return 0;
  else
    return x < 0 ? -1 : 1;
}
bool operator==(const Point &a, const Point &b) {
  return dcmp(a.x - b.x) == 0 && dcmp(a.y - b.y) == 0;
}
double Dot(Point A, Point B) { return A.x * B.x + A.y * B.y; }
double Length(Point A) { return sqrt(Dot(A, A)); }
double Angle(Point A, Point B) {
  return acos(Dot(A, B) / Length(A) / Length(B));
}
double Cross(Point A, Point B) { return A.x * B.y - A.y * B.x; }
double Area2(Point A, Point B, Point C) { return Cross(B - A, C - A); }
Point Rotate(Point A, double rad) {
  return Point(A.x * cos(rad) - A.y * sin(rad),
               A.x * sin(rad) + A.y * cos(rad));
}
struct Line {
  Point p, v;
  double ang;
  friend bool operator<(Line x, Line y) {
    return fabs(x.ang - y.ang) < eps ? Cross(x.v - x.p, y.v - x.p) > eps
                                     : x.ang - y.ang < eps;
  }
} a[1000], q[1000];
Point Jd(Line x, Line y) {
  Point P = x.p, Q = y.p;
  Point v = x.p - x.v, w = y.p - y.v;
  Point u = P - Q;
  double t = Cross(w, u) / Cross(v, w);
  return P + v * t;
}
double Dtl(Point P, Point A, Point B) {
  Point v1 = B - A, v2 = P - A;
  return fabs(Cross(v1, v2)) / Length(v1);
}
double Dts(Point P, Point A, Point B) {
  if (A == B) return Length(P - A);
  Point v1 = B - A, v2 = P - A, v3 = P - B;
  if (dcmp(Dot(v1, v2) < 0))
    return Length(v2);
  else if (dcmp(Dot(v1, v3)) > 0)
    return Length(v3);
  else
    return fabs(Cross(v1, v2)) / Length(v1);
}
Point Gjp(Point P, Point A, Point B) {
  Point v = B - A;
  return A + v * (Dot(v, P - A)) / (Dot(v, v));
}
bool Spi(Point a1, Point a2, Point b1, Point b2) {
  double c1 = Cross(a2 - a1, b1 - a1), c2 = Cross(a2 - a1, b2 - a1),
         c3 = Cross(b2 - b1, a1 - b1), c4 = Cross(b2 - b1, a2 - a1);
  return dcmp(c1) * dcmp(c2) < 0 && dcmp(c3) * dcmp(c4) < 0;
}
bool Onseg(Point p, Point a1, Point a2) {
  return dcmp(Cross(a1 - p, a2 - p)) == 0 && dcmp(Dot(a1 - p, a2 - p)) < 0;
}
double Parea(Point *p, int n) {
  double area = 0;
  p[n + 1] = p[1];
  for (int i = 1; i <= n; i++) area += Cross(p[i], p[i + 1]);
  return area / 2.0;
}
bool cmp(Point a, Point b) {
  if (fabs(a.x - b.x) > eps)
    return a.x + eps < b.x;
  else
    return a.y + eps < b.y;
}
bool cmp1(Point a, Point b) {
  double tmp = Cross(a, b);
  return tmp > 0 || (tmp == 0 && Length(a) < Length(b));
}
bool pd(Line i, Line j, Line k) {
  Point P = Jd(i, j);
  return Cross(k.v - k.p, P - k.p) < eps;
}
int ConvexHull(Point *p, Point *st, int n) {
  sort(p, p + n, cmp);
  int m = 0;
  for (int i = 0; i < n; i++) {
    while (m > 1 && Cross(st[m - 1] - st[m - 2], p[i] - st[m - 2]) >= 0) --m;
    st[m++] = p[i];
  }
  return m;
  int k = m;
  for (int i = n - 2; i >= 0; i--) {
    while (m > k && Cross(st[m - 1] - st[m - 2], p[i] - st[m - 2]) <= 0) --m;
    st[m++] = p[i];
  }
  if (n > 1) --m;
  return m;
}
int Half_Plane(Line *a, int la, Point *b) {
  sort(a + 1, a + 1 + la);
  int cnt = 0;
  for (int i = 1; i <= la; i++) {
    if (fabs(a[i].ang - a[i - 1].ang) > eps) cnt++;
    a[cnt] = a[i];
  }
  int head = 1, tail = 0;
  q[++tail] = a[1], q[++tail] = a[2];
  for (int i = 3; i <= cnt; i++) {
    while (head < tail && pd(q[tail - 1], q[tail], a[i])) tail--;
    while (head < tail && pd(q[head + 1], q[head], a[i])) head++;
    q[++tail] = a[i];
  }
  while (head < tail && pd(q[tail - 1], q[tail], q[head])) tail--;
  while (head < tail && pd(q[head + 1], q[head], q[tail])) head++;
  q[tail + 1] = q[head];
  cnt = 0;
  for (int i = head; i <= tail; i++) b[++cnt] = Jd(q[i], q[i + 1]);
  return cnt;
}
int n;
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    double x, y;
    cin >> x >> y;
    p[i] = Point(x, y - x * x);
  }
  int m = ConvexHull(p, st, n);
  if (st[0].x == st[1].x) m--;
  cout << m - 1 << endl;
  return 0;
}
