#pragma GCC optimize("Ofast")
// Copyright (C) 2003-2024 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/** @file stdc++.h
 *  This is an implementation file for a precompiled header.
 */

// 17.4.1.2 Headers

// C
#ifndef _GLIBCXX_NO_ASSERT
#include <cassert>
#endif
#include <cctype>
#include <cfloat>
#include <ciso646>
#include <climits>
#include <csetjmp>
#include <cstdarg>
#include <cstddef>
#include <cstdlib>

#if __cplusplus >= 201103L
#include <cstdint>
#endif

// C++
#include <bitset>
#include <complex>
#include <algorithm>
#include <bitset>
#include <functional>
#include <iterator>
#include <limits>
#include <memory>
#include <new>
#include <numeric>
#include <typeinfo>
#include <utility>

#if __cplusplus >= 201103L
#include <array>
#include <atomic>
#include <initializer_list>
#include <ratio>
#include <scoped_allocator>
#include <tuple>
#include <typeindex>
#include <type_traits>
#endif

#if __cplusplus >= 201402L
#endif

#if __cplusplus >= 201703L
#include <any>
// #include <execution>
#include <optional>
#include <variant>
#include <string_view>
#endif

#if __cplusplus >= 202002L
#include <bit>
#include <compare>
#include <concepts>
#include <numbers>
#include <ranges>
#include <span>
#include <source_location>
#include <version>
#endif

#if __cplusplus > 202002L
#include <expected>
#include <stdatomic.h>
#if __cpp_impl_coroutine
# include <coroutine>
#endif
#endif

// C
#ifndef _GLIBCXX_NO_ASSERT
#include <cassert>
#endif
#include <cctype>
#include <cerrno>
#include <cfloat>
#include <ciso646>
#include <climits>
#include <clocale>
#include <cmath>
#include <csetjmp>
#include <csignal>
#include <cstdarg>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <cwchar>
#include <cwctype>

#if __cplusplus >= 201103L
#include <ccomplex>
#include <cfenv>
#include <cinttypes>
#include <cstdbool>
#include <cstdint>
#include <ctgmath>
#include <cuchar>
#endif

// C++
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>

#if __cplusplus >= 201103L
#include <array>
#include <atomic>
#include <chrono>
#include <codecvt>
#include <condition_variable>
#include <forward_list>
#include <future>
#include <initializer_list>
#include <mutex>
#include <random>
#include <ratio>
#include <regex>
#include <scoped_allocator>
#include <system_error>
#include <thread>
#include <tuple>
#include <typeindex>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#endif

#if __cplusplus >= 201402L
#include <shared_mutex>
#endif

#if __cplusplus >= 201703L
#include <any>
#include <charconv>
// #include <execution>
#include <filesystem>
#include <optional>
#include <memory_resource>
#include <variant>
#endif

#if __cplusplus >= 202002L
#include <barrier>
#include <bit>
#include <compare>
#include <concepts>
#include <format>
#include <latch>
#include <numbers>
#include <ranges>
#include <span>
#include <stop_token>
#include <semaphore>
#include <source_location>
#include <syncstream>
#include <version>
#endif

#if __cplusplus > 202002L
#include <expected>
#include <generator>
#include <print>
#include <spanstream>
#if __has_include(<stacktrace>)
# include <stacktrace>
#endif
#include <stdatomic.h>
#include <stdfloat>
#endif

#if __cplusplus > 202302L
#include <text_encoding>
#endif

namespace std {
    template<typename T>
    int __lg(T x) {
        assert(x > 0);
        int ans = 0;
        while (x > 0) {
            ans += 1;
            x >>= 1;
        }
        return ans - 1;
    }
}
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep1(i, n) for (int i = 1; i < (n); ++i)
#define rep1n(i, n) for (int i = 1; i <= (n); ++i)
#define repr(i, n) for (int i = (n) - 1; i >= 0; --i)
#define pb push_back
#define eb emplace_back
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define each(x, a) for (auto &x : a)
#define ar array
#define vec vector
#define range(i, n) rep(i, n)

using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;
using str = string;
using pi = pair<int, int>;
using pl = pair<ll, ll>;

using vi = vector<int>;
using vl = vector<ll>;
using vpi = vector<pair<int, int>>;
using vvi = vector<vi>;

int Bit(int mask, int b) { return (mask >> b) & 1; }

template<class T>
bool ckmin(T &a, const T &b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}

template<class T>
bool ckmax(T &a, const T &b) {
    if (b > a) {
        a = b;
        return true;
    }
    return false;
}

// [l, r)
template<typename T, typename F>
T FindFirstTrue(T l, T r, const F &predicat) {
    --l;
    while (r - l > 1) {
        T mid = l + (r - l) / 2;
        if (predicat(mid)) {
            r = mid;
        } else {
            l = mid;
        }
    }
    return r;
}


template<typename T, typename F>
T FindLastFalse(T l, T r, const F &predicat) {
    return FindFirstTrue(l, r, predicat) - 1;
}


const ll INF = 2e18;
const int INFi = 1e9;
const int N = 3e5 + 5;
const int LG = 20;

struct Point {
    int x, y;

    Point(int x_ = 0, int y_ = 0) : x(x_), y(y_) {}

    Point operator-(const Point &oth) const {
        return {x - oth.x, y - oth.y};
    }


    ll operator*(const Point &oth) const {
        return 1ll * x * oth.y - 1ll * y * oth.x;
    }

    ll length() const {
        return 1ll * x * x + 1ll * y * y;
    }
};

using pt = Point;

vector<pt> A;

int ang_type(int a, int b, int c) {
    ll v = (A[b] - A[a]) * (A[c] - A[b]);
    if (v > 0) return 1;
    if (v < 0) return 2;
    return 0;
}

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int SZ = 300;
int tp[SZ][SZ][SZ];

pair<vector<Point>, vector<Point>> convex_hull(vector<Point> a) {
    int n = a.size();
    for (int i = 1; i < n; i++) {
        if (make_pair(a[i].x, a[i].y) < make_pair(a[0].x, a[0].y)) {
            swap(a[i], a[0]);
        }
    }

    sort(1 + all(a), [&](Point p, Point q) {
        p = p - a[0];
        q = q - a[0];
        ll prod = p * q;
        if (prod != 0) {
            return prod > 0;
        }
        return p.length() < q.length();
    });

    vector<Point> hull = {a[0], a[1]}, rem;
    for (int i = 2; i < n; i++) {
        while ((hull.back() - hull[int(hull.size()) - 2]) * (a[i] - hull.back()) < 0) {
            rem.push_back(hull.back());
            hull.pop_back();
        }
        hull.push_back(a[i]);
    }
    return {hull, rem};
}

void solve() {
    int n;
    cin >> n;
    A.resize(n);
    rep(i, n) cin >> A[i].x >> A[i].y;

    auto [lol, kek] = convex_hull(A);
    shuffle(all(lol), rng);
    shuffle(all(kek), rng);

    A.clear();
    int l = 0, r = 0;
    for (int i = 0; i < n; i++) {
        if (l < lol.size()) {
            A.push_back(lol[l++]);
        }
        if (r < kek.size()) {
            A.push_back(kek[r++]);
        }
    }

    for (int s0 = 0; s0 < n; ++s0) {
        if (clock() / (1.0 * CLOCKS_PER_SEC) >= 1.0) {
            break;
        }
        for(int i = 0; i < s0; ++i) {
            for(int j = 0; j < s0; ++j) {
                if (i == j) continue;
                tp[i][j][s0] = ang_type(i, j, s0);
                tp[i][s0][j] = ang_type(i, s0, j);
                tp[s0][i][j] = ang_type(s0, i, j);
            }
        }
        rep(s1, s0) {
            rep(s2, s0) {
                if (s2 == s1) continue;
                rep(s3, s0) {
                    if (s3 == s1 || s3 == s2 || tp[s0][s1][s2] == tp[s1][s2][s3]) continue;
                    rep(s4, s0) {
                        if (s4 == s3 || s4 == s2 || s4 == s1 || tp[s1][s2][s3] == tp[s2][s3][s4]) continue;
                        rep(s5, s1) {
                            if (s1 == s5 || s2 == s5 || s5 == s3 || s5 == s4 || tp[s2][s3][s4] == tp[s3][s4][s5] || tp[s3][s4][s5] == tp[s4][s5][s0] || tp[s4][s5][s0] == tp[s5][s0][s1] || tp[s5][s0][s1] == tp[s0][s1][s2]) continue;
                            cout << "6\n";
                            cout << A[s0].x << ' ' << A[s0].y << '\n';
                            cout << A[s1].x << ' ' << A[s1].y << '\n';
                            cout << A[s2].x << ' ' << A[s2].y << '\n';
                            cout << A[s3].x << ' ' << A[s3].y << '\n';
                            cout << A[s4].x << ' ' << A[s4].y << '\n';
                            cout << A[s5].x << ' ' << A[s5].y << '\n';
                            return;
                        }
                    }
                }
            }
        }
    }

    {shuffle(all(A), rng);
        for (int s = 5; s < n; ++s) {
            if (clock() / (1.0 * CLOCKS_PER_SEC) >= 1.8) {
                break;
            }
            for (int i = 0; i < s; ++i) {
                for (int st = 1; st <= 2; ++st) {
                    vector<vector<vi>> dp(1 << s, vector<vi>(s, vi(s, 0)));
                    rep(j, s) {
                        if (i == j) continue;
                        int q = ang_type(s, i, j);
                        if (q != st) continue;
                        dp[(1 << i) | (1 << j)][j][i] |= q;
                    }
                    ar<int, 4> answer = {-1, -1, -1, -1};
                    rep(mask, 1 << s) {
                        if (__builtin_popcount(mask) > 5) continue;
                        rep(last, s) {
                            rep(plast, s) {
                                if (!dp[mask][last][plast]) continue;
                                rep(nxt, s + 1) {
                                    if ((1 << nxt) & mask) continue;
                                    int v = ang_type(plast, last, nxt);
                                    assert(v);
                                    if (dp[mask][last][plast] & (v ^ 3)) {
                                        if (nxt == s) {
                                            if (v != st) continue;
                                            if (ang_type(last, s, i) == st) continue;
                                            answer = {mask, last, plast, v ^ 3};
                                            break;
                                        }
                                        dp[mask | (1 << nxt)][nxt][last] |= v;
                                    }
                                }
                                if (answer[0] != -1) break;
                            }
                            if (answer[0] != -1) break;
                        }
                        if (answer[0] != -1) break;
                    }

                    if (answer[0] == -1) continue;

                    vi p;
                    int mask = answer[0];
                    int last = answer[1];
                    int plast = answer[2];
                    int v = answer[3];
                    while (__builtin_popcount(mask) != 2) {
                        assert(dp[mask][last][plast] & v);
                        p.push_back(last);
                        mask ^= (1 << last);
                        bool ok = false;
                        rep(pplast, s) {
                            if (((1 << pplast) & mask) && pplast != plast) {
                                int tv = ang_type(pplast, plast, last);
                                if (tv != v) continue;
                                if (dp[mask][plast][pplast] & (tv ^ 3)) {
                                    ok = true;
                                    last = plast;
                                    plast = pplast;
                                    v ^= 3;
                                    break;
                                }
                            }
                        }
                        assert(ok);
                    }
                    p.push_back(last);
                    p.push_back(plast);
                    p.push_back(s);
                    reverse(all(p));

                    assert(p.size() % 2 == 0);
                    assert(p.size() == 6);
                    cout << p.size() << '\n';
                    rep(t, p.size()) {
                        cout << A[p[t]].x << ' ' << A[p[t]].y << '\n';
                    }

                    return;
                }
            }
        }}

    cout << "-1\n";
}


signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(12) << fixed;
    int t = 1;
//    cin >> t;
    rep(i, t) {
        solve();
    }
//    cout << sizeof(a) / 1'000'000 << '\n';
    return 0;
}