#include <bits/stdc++.h>
using namespace std;
/* basics */
namespace geo {
#define EPS 1e-8
template <typename T, enable_if_t<is_integral<T>::value, bool> = true>
int sign(T x) { return (x > 0) - (x < 0); }
template <typename T, enable_if_t<is_floating_point<T>::value, bool> = true>
int sign(T x) { return (x > EPS) - (x < -EPS); }
}; // namespace geo
/* point2D */
namespace geo {
template <typename T>
struct point2D {
T x, y;
point2D() = default;
point2D(T _x, T _y) : x(_x), y(_y) {}
template <typename U>
explicit point2D(const point2D<U>& p) : x(p.x), y(p.y) {}
using P = point2D;
bool operator<(const P& p) const { return tie(x, y) < tie(p.x, p.y); }
bool operator==(const P& p) const { return tie(x, y) == tie(p.x, p.y); }
bool operator!=(const P& p) const { return tie(x, y) != tie(p.x, p.y); }
friend P operator+(const P& a, const P& b) { return P(a.x + b.x, a.y + b.y); }
friend P operator-(const P& a, const P& b) { return P(a.x - b.x, a.y - b.y); }
friend P operator*(const P& a, const T& scalar) { return P(a.x * scalar, a.y * scalar); }
friend P operator*(const T& scalar, const P& a) { return P(scalar * a.x, scalar * a.y); }
friend P operator/(const P& a, const T& scalar) { return P(a.x / scalar, a.y / scalar); }
friend ostream& operator<<(ostream& o, const P& p) { return o << '(' << p.x << ", " << p.y << ')'; }
friend istream& operator>>(istream& i, P& p) { return i >> p.x >> p.y; }
T dot(const P& p) const { return x * p.x + y * p.y; }
T cross(const P& p) const { return x * p.y - y * p.x; }
T cross(const P& a, const P& b) const { return (a - *this).cross(b - *this); }
T dist2() const { return x * x + y * y; }
double dist() const { return sqrt(dist2()); }
P perp_cw() const { return P(y, -x); }
P perp_ccw() const { return P(-y, x); }
P unit() const { return *this / dist(); }
P normal() const { return perp_ccw().unit(); }
P unit_int() const { return x || y ? *this / gcd(x, y) : *this; }
P normal_int() const { return perp_ccw().unit_int(); }
bool same_dir(const P& p) const { return cross(p) == 0 && dot(p) > 0; }
int side_of(const P& s, const P& e) const {
if constexpr (is_integral_v<T>) {
return sign(s.cross(e, *this));
} else {
auto res = (e - s).cross(*this - s);
double l = (e - s).dist() * EPS;
return (res > l) - (res < -l);
}
}
double angle() const { return atan2(y, x); }
P rotate(double radian) const {
return P(x * cos(radian) - y * sin(radian), x * sin(radian) + y * cos(radian));
}
};
}; // namespace geo
int main() {
cin.tie(nullptr)->sync_with_stdio(false);
#ifdef palilo
freopen("in", "r", stdin);
freopen("out", "w", stdout);
#endif
using point = geo::point2D<int64_t>;
int n;
cin >> n;
vector<point> a(n);
for (auto& p : a) cin >> p;
swap(a.back(), *min_element(a.begin(), a.end(), [&](const auto& lhs, const auto& rhs) {
return lhs.y < rhs.y;
}));
sort(a.begin(), a.end() - 1, [&](const auto& lhs, const auto& rhs) {
return a.back().cross(lhs, rhs) < 0;
});
// {#, prev id}
vector gol(n, -1), garak(n, 1);
vector gol_prev(n, n - 1), garak_prev(n, n - 1);
for (int i = 1; i < n; ++i) {
for (int j = 0; j < i; ++j) {
if (i != n - 1 && a.back().cross(a[j], a[i]) == 0) break;
if (a[i].side_of(a[garak_prev[j]], a[j]) == -1) {
if (gol[i] < garak[j] + 1 || (gol[i] == garak[j] + 1 && a[j].side_of(a[gol_prev[i]], a[i]) == 1))
gol[i] = garak[j] + 1, gol_prev[i] = j;
}
if (a[i].side_of(a[gol_prev[j]], a[j]) == 1) {
if (garak[i] < gol[j] + 1 || (garak[i] == gol[j] + 1 && a[j].side_of(a[garak_prev[i]], a[i]) == -1))
garak[i] = gol[j] + 1, garak_prev[i] = j;
}
}
}
if (gol.back() < 4) return cout << 0, 0;
vector<int> ans;
ans.reserve(gol.back());
for (int flag = 1, i = n - 1, cnt = gol.back(); cnt--; flag ^= 1) {
ans.emplace_back(i);
i = (flag ? gol_prev : garak_prev)[i];
}
cout << ans.size() << '\n';
for (const auto& id : ans)
cout << a[id].x << ' ' << a[id].y << '\n';
}
