#include <bits/stdc++.h>
const double EPS = 1e-4;
struct Point {
  double x, y;
  Point(const double d = 0.0) : x(d), y(d) {}
  Point(const double x, const double y) : x(x), y(y) {}
};
struct Segment {
  Point initial, terminal;
  Segment(const Point& initial, const Point& terminal)
      : initial(initial), terminal(terminal) {}
  Segment(const double x1, const double y1, const double x2, const double y2)
      : initial(x1, y1), terminal(x2, y2) {}
};
struct Line {
  Point initial, terminal;
  Line(const Point& initial, const Point& terminal)
      : initial(initial), terminal(terminal) {}
  Line(const double x1, const double y1, const double x2, const double y2)
      : initial(x1, y1), terminal(x2, y2) {}
  Line(const Segment& s) : initial(s.initial), terminal(s.terminal) {}
};
bool relative_equal(const double d1, const double d2) {
  return d1 == 0 ? std::abs(d2) < EPS : std::abs((d1 - d2) / d1) < EPS;
}
bool operator==(const Point& lhs, const Point& rhs) {
  return relative_equal(lhs.x, rhs.x) && relative_equal(lhs.y, rhs.y);
}
bool operator<(const Point& lhs, const Point& rhs) {
  return lhs.x != rhs.x ? lhs.x < rhs.x : lhs.y < rhs.y;
}
bool operator>(const Point& lhs, const Point& rhs) {
  return lhs.x != rhs.x ? lhs.x > rhs.x : lhs.y > rhs.y;
}
bool operator!=(const Point& lhs, const Point& rhs) { return !(lhs == rhs); }
bool operator<=(const Point& lhs, const Point& rhs) { return !(lhs > rhs); }
bool operator>=(const Point& lhs, const Point& rhs) { return !(lhs < rhs); }
const Point operator+(const Point& lhs, const Point& rhs) {
  return Point(lhs.x + rhs.x, lhs.y + rhs.y);
}
const Point operator-(const Point& lhs, const Point& rhs) {
  return Point(lhs.x - rhs.x, lhs.y - rhs.y);
}
const Point operator*(const Point& lhs, const Point& rhs) {
  return Point(lhs.x * rhs.x, lhs.y * rhs.y);
}
const Point operator/(const Point& lhs, const Point& rhs) {
  return Point(lhs.x / rhs.x, lhs.y / rhs.y);
}
const Point operator-(const Point& p) { return Point(-p.x, -p.y); }
double abs(const Point& p) { return std::hypot(p.x, p.y); }
double norm(const Point& p) { return p.x * p.x + p.y * p.y; }
double dot(const Point& a, const Point& b) { return a.x * b.x + a.y * b.y; }
double cross(const Point& a, const Point& b) { return a.x * b.y - a.y * b.x; }
bool parallel(const Line& l1, const Line& l2) {
  return std::abs(cross(l2.terminal - l2.initial, l1.terminal - l1.initial)) <
         EPS;
}
bool orthogonal(const Line& l1, const Line& l2) {
  return std::abs(dot(l2.terminal - l2.initial, l1.terminal - l1.initial)) <
         EPS;
}
enum POSITION {
  ONLINE_FRONT = -2,
  CLOCKWISE,
  ON_SEGMENT,
  COUNTER_CLOCKWISE,
  ONLINE_BACK
};
POSITION ccw(const Point& a, const Point& b, const Point& p) {
  Point v1 = b - a;
  Point v2 = p - a;
  if (cross(v1, v2) >= EPS) return COUNTER_CLOCKWISE;
  if (cross(v1, v2) <= -EPS) return CLOCKWISE;
  if (dot(v1, v2) <= -EPS) return ONLINE_BACK;
  if (norm(v1) < norm(v2)) return ONLINE_FRONT;
  return ON_SEGMENT;
}
bool intersect(const Point& p1, const Point& p2) { return p1 == p2; }
bool intersect(const Point& p, const Segment& s) {
  return abs(p - s.initial) + abs(p - s.terminal) -
             abs(s.initial - s.terminal) <=
         EPS;
}
bool intersect(const Segment& s, const Point& p) { return intersect(p, s); }
bool intersect(const Point& p, const Line& l) {
  return !parallel(Line(p, l.initial), Line(p, l.terminal));
}
bool intersect(const Line& l, const Point& p) { return intersect(p, l); }
bool intersect(const Segment& s1, const Segment& s2) {
  return ccw(s1.initial, s1.terminal, s2.initial) *
                 ccw(s1.initial, s1.terminal, s2.terminal) <=
             0 &&
         ccw(s2.initial, s2.terminal, s1.initial) *
                 ccw(s2.initial, s2.terminal, s1.terminal) <=
             0;
}
bool intersect(const Segment& s, const Line& l) {
  auto v1 = l.terminal - l.initial;
  auto v2 = s.initial - l.initial;
  auto v3 = s.terminal - l.initial;
  return cross(v1, v2) * cross(v1, v3) <= EPS;
}
bool intersect(const Line& l, const Segment& s) { return intersect(s, l); }
bool intersect(const Line& l1, const Line& l2) {
  return !parallel(l1, l2) || intersect(l1.initial, l2);
}
Point projection(const Point& p, const Line& l) {
  auto v = l.initial - l.terminal;
  return l.initial + dot(p - l.initial, v) / norm(v) * v;
}
Point projection(const Line& l, const Point& p) { return projection(p, l); }
Point reflection(const Point& p, const Line& l) {
  return p + 2 * (projection(p, l) - p);
}
Point reflection(const Line& l, const Point& p) { return reflection(p, l); }
double distance(const Point& p1, const Point& p2) {
  auto p = p1 - p2;
  return hypot(p.x, p.y);
}
double distance(const Point& p, const Segment& s) {
  auto r = projection(s, p);
  return intersect(r, s)
             ? distance(p, r)
             : std::min(distance(p, s.initial), distance(p, s.terminal));
}
double distance(const Segment& s, const Point& p) { return distance(p, s); }
double distance(const Point& p, const Line& l) {
  return distance(p, projection(p, l));
}
double distance(const Line& l, const Point& p) { return distance(p, l); }
double distance(const Segment& s1, const Segment& s2) {
  return intersect(s1, s2)
             ? 0.0
             : std::min({distance(s1, s2.initial), distance(s1, s2.terminal),
                         distance(s2, s1.initial), distance(s2, s1.terminal)});
}
double distance(const Segment& s, const Line& l) {
  return intersect(s, l)
             ? 0.0
             : std::min(distance(s.initial, l), distance(s.terminal, l));
}
double distance(const Line& l, const Segment& s) { return distance(s, l); }
double distance(const Line& l1, const Line& l2) {
  return intersect(l1, l2) ? 0.0 : distance(l1.initial, l2);
}
const Point crosspoint(const Line& l1, const Line& l2) {
  assert(intersect(l1, l2));
  if (parallel(l1, l2)) return l1.initial;
  double A = cross(l1.terminal - l1.initial, l2.terminal - l2.initial);
  double B = cross(l1.terminal - l1.initial, l1.terminal - l2.initial);
  return l2.initial + B / A * (l2.terminal - l2.initial);
}
const Point crosspoint(const Segment& s, const Line& l) {
  assert(intersect(s, l));
  if (parallel(s, l)) return s.initial;
  Point cp = crosspoint(Line(s), l);
  assert(intersect(s, cp));
  return cp;
}
const Point crosspoint(const Line& l, const Segment& s) {
  return crosspoint(s, l);
}
const Point crosspoint(const Segment& s1, const Segment& s2) {
  assert(intersect(s1, s2));
  if (parallel(s1, s2)) {
    if (intersect(s1.initial, s2)) return s1.initial;
    if (intersect(s1.terminal, s2)) return s1.terminal;
    if (intersect(s2.initial, s1)) return s2.initial;
    if (intersect(s2.terminal, s1)) return s2.terminal;
  }
  return crosspoint(Line(s1), Line(s2));
}
class Polygon {
 public:
  void add(const Point& p) {
    if (!vertex_.empty()) {
      if (!edge_.empty()) edge_.pop_back();
      edge_.push_back(Segment(vertex_.back(), p));
      edge_.push_back(Segment(p, vertex_.front()));
    }
    vertex_.push_back(p);
  }
  void clear() {
    vertex_.clear();
    edge_.clear();
  };
  int size() const { return vertex_.size(); }
  Point vertex(const int n) const { return vertex_.at(n); }
  Segment edge(const int n) const { return edge_.at(n); }
  const std::vector<Point>& vertex() const { return vertex_; }
  const std::vector<Segment>& edge() const { return edge_; }
  bool touch(const Point& p) const {
    return std::any_of(edge().begin(), edge().end(), [=](const Segment& s) {
      return ccw(s.initial, s.terminal, p) == ON_SEGMENT;
    });
  }
  bool intersect(const Point& p) const {
    bool in = false;
    for (const auto& e : edge()) {
      if (::intersect(p, e)) return true;
      Point a = e.initial - p;
      Point b = e.terminal - p;
      if (a.y > b.y) std::swap(a, b);
      if (a.y < EPS && EPS <= b.y && cross(a, b) < EPS) in = !in;
    }
    return in;
  }
  double area() const {
    return std::abs(std::accumulate(edge().begin(), edge().end(), 0,
                                    [=](const int sum, const Segment& e) {
                                      return sum + cross(e.initial, e.terminal);
                                    })) /
           2.0;
  }
  bool convex() const {
    bool positive = false;
    bool negative = false;
    for (int i = 0; i < size(); ++i) {
      auto position =
          ccw(vertex(i), vertex((i + 1) % size()), vertex((i + 2) % size()));
      positive |= position == CLOCKWISE;
      negative |= position == COUNTER_CLOCKWISE;
      if (negative && positive) return false;
    }
    return true;
  }

 private:
  std::vector<Point> vertex_;
  std::vector<Segment> edge_;
};
using namespace std;
void print(const Point& p) { cout << "" << p.x << " " << p.y << ""; }
void print(const Segment& l) {
  print(l.initial);
  cout << " ";
  print(l.terminal);
}
void print(const Line& l) {
  print(l.initial);
  cout << " ";
  print(l.terminal);
}
using namespace std;
const int N = 16;
int n;
Polygon polygon;
vector<Segment> segment;
int check(bitset<N> bit) {
  for (int i = 0; i < segment.size(); ++i) {
    bool ok = false;
    for (int v = 0; v < polygon.vertex().size(); ++v) {
      if (!bit[v]) continue;
      if (!polygon.intersect(
              (polygon.vertex(v) + segment[i].initial + segment[i].terminal) /
              3.0))
        continue;
      Point median = (segment[i].initial + segment[i].terminal) / 2.0;
      Segment s(polygon.vertex(v), median);
      if (all_of(polygon.edge().begin(), polygon.edge().end(),
                 [=](const Segment& wall) {
                   if (parallel(s, wall)) return true;
                   if (!intersect(s, wall)) return true;
                   Point cp = crosspoint(s, wall);
                   if (cp == s.initial) return true;
                   if (cp == s.terminal) return true;
                   return false;
                 }))
        ok = true;
    }
    if (!ok) return N;
  }
  return bit.count();
}
int solve(const int depth = 0, bitset<N> bit = 0) {
  return depth < n ? min(solve(depth + 1, bit.reset(depth)),
                         solve(depth + 1, bit.set(depth)))
                   : check(bit);
}
vector<Segment> split() {
  vector<vector<Point>> point(polygon.edge().size());
  for (int i = 0; i < polygon.edge().size(); ++i) {
    point[i].push_back(polygon.edge(i).initial);
    point[i].push_back(polygon.edge(i).terminal);
  }
  for (int i = 0; i < polygon.vertex().size(); ++i) {
    for (int j = i + 1; j < polygon.vertex().size(); ++j) {
      Segment l(polygon.vertex(i), polygon.vertex(j));
      for (int k = 0; k < polygon.edge().size(); ++k) {
        if (parallel(l, polygon.edge(k))) continue;
        if (!intersect(l, polygon.edge(k))) continue;
        Point cp = crosspoint(l, polygon.edge(k));
        point[k].push_back(cp);
      }
    }
  }
  vector<Segment> result;
  for (auto& p : point) {
    sort(p.begin(), p.end());
    p.erase(unique(p.begin(), p.end()), p.end());
    for (int i = 1; i < p.size(); ++i)
      result.push_back(Segment(p[i - 1], p[i]));
  }
  return result;
}
int main() {
  while (cin >> n, n) {
    polygon.clear();
    for (int i = 0; i < n; ++i) {
      double x, y;
      cin >> x >> y;
      polygon.add({x, y});
    }
    segment = split();
    cout << solve() << endl;
  }
}
