#include <algorithm>
#include <bitset>
#include <cassert>
#include <chrono>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <queue>
#include <random>
#include <regex>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <sys/timeb.h>
#include <vector>

using namespace std;

#define repr(i, a, b) for (int i = (int)(a); i < (int)(b); i++)
#define rep(i, n) repr(i, 0, n)
#define reprrev(i, a, b) for (int i = (int)(b)-1; i >= (int)(a); i--)
#define reprev(i, n) reprrev(i, 0, n)
#define repi(itr, ds) for (auto itr = ds.begin(); itr != ds.end(); itr++)
#define chmin(mi, val) mi = min(mi, val)
#define chmax(ma, val) ma = max(ma, val)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define mp make_pair
#define mt make_tuple
#define INF 1050000000
#define INFR INT_MAX
#define INFL (long long)(4e18)
#define INFLR LLONG_MAX
#define EPS (1e-10)
#define MOD 1000000007
// #define MOD 998244353
#define PI 3.141592653589793238
#define RMAX 4294967295

typedef long long ll;
typedef pair<int, int> Pi;
typedef pair<ll, ll> Pll;
typedef pair<double, double> Pd;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<bool> vb;
typedef vector<char> vc;
typedef vector<string> vs;
typedef vector<double> vd;
typedef vector<Pi> vPi;
typedef vector<Pll> vPll;
typedef vector<Pd> vPd;
typedef vector<vector<int>> vvi;
typedef vector<vector<bool>> vvb;
typedef vector<vector<ll>> vvll;
typedef vector<vector<char>> vvc;
typedef vector<vector<string>> vvs;
typedef vector<vector<double>> vvd;
typedef vector<vector<Pi>> vvPi;
typedef vector<vector<vector<int>>> vvvi;
typedef vector<vector<vector<ll>>> vvvll;
typedef vector<vector<vector<Pi>>> vvvPi;
typedef vector<vector<vector<vector<Pi>>>> vvvvPi;
typedef priority_queue<int, vector<int>, greater<int>> pqli;
typedef priority_queue<ll, vector<ll>, greater<ll>> pqlll;
typedef priority_queue<Pi, vector<Pi>, greater<Pi>> pqlP;
template <class T>
using vec = vector<T>;
template <class T>
using pql = priority_queue<T, vector<T>, greater<T>>;

// vvvvvvvvvvvvvvvvvvvvvvv debug output vvvvvvvvvvvvvvvvvvvvvvv
// vector
template <typename T>
istream &operator>>(istream &is, vector<T> &vec) {
    for (T &x : vec) is >> x;
    return is;
}
// pair
template <typename T, typename U>
ostream &operator<<(ostream &os, pair<T, U> &pair_var) {
    os << "(" << pair_var.first << "," << pair_var.second << ")";
    return os;
}
// pair
template <typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &pair_var) {
    os << "(" << pair_var.first << "," << pair_var.second << ")";
    return os;
}
// vector
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &vec) {
    os << "{";
    for (int i = 0; i < vec.size(); i++) {
        os << vec[i] << (i + 1 == vec.size() ? "" : ", ");
    }
    os << "}";
    return os;
}
// map
template <typename T, typename U>
ostream &operator<<(ostream &os, map<T, U> &map_var) {
    os << "{";
    repi(itr, map_var) {
        os << "(" << itr->first << "," << itr->second << ")";
        itr++;
        if (itr == map_var.end()) os << ", ";
        itr--;
    }
    os << "}";
    return os;
}
// set
template <typename T>
ostream &operator<<(ostream &os, set<T> &set_var) {
    os << "{";
    repi(itr, set_var) {
        os << "  " << *itr << endl;
        itr++;
        if (itr == set_var.end()) os << ", ";
        itr--;
    }
    os << "}";
    return os;
}

#define DUMPOUT cerr

void dump_func() {
    DUMPOUT << endl;
}
template <class Head, class... Tail>
void dump_func(Head &&head, Tail &&... tail) {
    DUMPOUT << head;
    if (sizeof...(Tail) > 0) {
        DUMPOUT << ", ";
    }
    dump_func(std::move(tail)...);
}
#ifdef DEBUG_
#define DEB
#define dump(...)                                                              \
    DUMPOUT << "  " << string(#__VA_ARGS__) << ": "                            \
            << "[" << to_string(__LINE__) << ":" << __FUNCTION__ << "]"        \
            << endl                                                            \
            << "    ",                                                         \
        dump_func(__VA_ARGS__)
#else
#define DEB if (false)
#define dump(...)
#endif

// ^^^^^^^^^^^^^^^^^^^^^^^ debug output ^^^^^^^^^^^^^^^^^^^^^^^

string YN(bool y, int id = 0) {
    if (id) cout << id;
    return (y ? "YES" : "NO");
}
string yn(bool y, int id = 0) {
    if (id) cout << id;
    return (y ? "Yes" : "No");
}
string ON(bool y, int id = 0) {
    if (id) cout << id;
    return (y ? "OK" : "NG");
}

int dir4[4][2] = {{0, -1}, {-1, 0}, {1, 0}, {0, 1}};
int dir8[8][2] = {{-1, -1}, {0, -1}, {1, -1}, {-1, 0},
                  {1, 0},   {-1, 1}, {0, 1},  {1, 1}};
char dirchar[4] = {'<', '^', '>', 'v'};

// [a,b)
int irand(int a, int b) {
    static mt19937 Rand(static_cast<unsigned int>(time(nullptr)));
    uniform_int_distribution<int> dist(a, b - 1);
    return dist(Rand);
}

// [a,b)
double drand(int a, int b) {
    static mt19937 Rand(static_cast<unsigned int>(time(nullptr)));
    uniform_real_distribution<double> dist(a, b);
    return dist(Rand);
}

// https://qiita.com/IgnorantCoder/items/3101d6276e9bdddf872c
template <typename A, typename F>
inline auto transform(const A &v, F &&f) {
    using result_type =
        decltype(std::declval<F>()(std::declval<typename A::value_type>()));
    vector<result_type> y(v.size());
    std::transform(std::cbegin(v), std::cend(v), std::begin(y), f);
    return y;
}

// 多次元vector生成
template <class T>
vector<T> make_v(size_t size, const T &init) {
    return vector<T>(size, init);
}
template <class... Ts>
auto make_v(size_t size, Ts... rest) {
    return vector<decltype(make_v(rest...))>(size, make_v(rest...));
}

template <typename T>
T max(vector<T> a) {
    return *max_element(all(a));
}
template <typename T>
T min(vector<T> a) {
    return *min_element(all(a));
}
template <typename T>
T sum(vector<T> a) {
    return accumulate(all(a), (T)0);
}

// mapでカウントとかする
template <typename T>
void add(map<T, int> &m, T item) {
    if (m.find(item) == m.end()) {
        m[item] = 1;
    } else {
        m[item]++;
    }
}

// デフォルト値つきのmapのget
template <typename T, typename U>
U get(map<T, U> m, T key, U def) {
    if (m.find(key) == m.end()) {
        return def;
    } else {
        return m[key];
    }
}

template <typename T>
bool contains(set<T> t, const T &key) {
    return t.find(key) != t.end();
}

template <typename T, typename U>
bool contains(map<T, U> t, const T &key) {
    return t.find(key) != t.end();
}

struct Edge {
    int from, to, cost;
    bool operator<(Edge e) {
        return cost < e.cost;
    }
};

using Graph = vec<vec<Edge>>;
ostream &operator<<(ostream &os, Edge &edge) {
    os << "(" << edge.from << "->" << edge.to << ":" << edge.cost << ")";
    return os;
}

//======================================================

template <class T>
class SegTree {
    int n;                     // 葉の数
    vector<pair<T, int>> data; // データを格納するvector
    T def;                     // 初期値かつ単位元
    function<pair<T, int>(pair<T, int>, pair<T, int>)>
        operation;            // 区間クエリで使う処理
    function<T(T, T)> update; // 点更新で使う処理

    // 区間[a,b)の総和。ノードk=[l,r)に着目している。
    pair<T, int> _query(int a, int b, int k, int l, int r) {
        if (r <= a || b <= l) return mp(def, -1); // 交差しない
        if (a <= l && r <= b)
            return data[k]; // a,l,r,bの順で完全に含まれる
        else {
            pair<T, int> c1 = _query(a, b, 2 * k + 1, l, (l + r) / 2); // 左の子
            pair<T, int> c2 = _query(a, b, 2 * k + 2, (l + r) / 2, r); // 右の子
            return operation(c1, c2);
        }
    }

  public:
    // _n:必要サイズ, _def:初期値かつ単位元, _operation:クエリ関数,
    // _update:更新関数
    SegTree(size_t _n, T _def,
            function<pair<T, int>(pair<T, int>, pair<T, int>)> _operation,
            function<T(T, T)> _update)
        : def(_def), operation(_operation), update(_update) {
        n = 1;
        while (n < _n) {
            n *= 2;
        }
        data = vector<pair<T, int>>(2 * n - 1);
        rep(i, 2 * n - 1) {
            data[i] = mp(def, i - n + 1);
        }
    }

    // 場所i(0-indexed)の値をxで更新
    void change(int i, T x) {
        i += n - 1;
        data[i] = mp(update(data[i].first, x), i - n + 1);
        while (i > 0) {
            i = (i - 1) / 2;
            data[i] = operation(data[i * 2 + 1], data[i * 2 + 2]);
        }
    }

    // [a, b)の区間クエリを実行
    pair<T, int> query(int a, int b) {
        return _query(a, b, 0, 0, n);
    }

    // 添字でアクセス
    T operator[](int i) {
        return data[i + n - 1];
    }
};

vi solve(SegTree<ll> &odd, SegTree<ll> &even, int N) {
    pql<pair<int, pair<int, int>>> Q;
    Q.push(mp(0, mp(0, N)));
    vi ans;
    ans.reserve(N);
    while (!Q.empty()) {
        auto item = Q.top();
        Q.pop();
        int l = item.second.first;
        int r = item.second.second;
        dump(l, r);

        if (l % 2 == 0) {
            auto pl2 = even.query(l, r);
            auto pr2 = odd.query(pl2.second, r);
            ans.push_back(pl2.first);
            ans.push_back(pr2.first);
            int l2 = pl2.second;
            int r2 = pr2.second;
            dump(l2, r2);

            if (l != l2) {
                Q.push(mp(even.query(l, l2).first, mp(l, l2)));
            }
            if (l2 + 1 != r2) {
                Q.push(mp(odd.query(l2 + 1, r2).first, mp(l2 + 1, r2)));
            }
            if (r2 + 1 != r) {
                Q.push(mp(even.query(r2 + 1, r).first, mp(r2 + 1, r)));
            }
        } else {
            auto pl2 = odd.query(l, r);
            auto pr2 = even.query(pl2.second, r);
            ans.push_back(pl2.first);
            ans.push_back(pr2.first);
            int l2 = pl2.second;
            int r2 = pr2.second;
            dump(l2, r2);

            if (l != l2) {
                Q.push(mp(odd.query(l, l2).first, mp(l, l2)));
            }
            if (l2 + 1 != r2) {
                Q.push(mp(even.query(l2 + 1, r2).first, mp(l2 + 1, r2)));
            }
            if (r2 + 1 != r) {
                Q.push(mp(odd.query(r2 + 1, r).first, mp(r2 + 1, r)));
            }
        }
    }
    return ans;
}

int main(void) {
    int N;
    cin >> N;
    SegTree<ll> odd(N, INFL,
                    [](pair<ll, int> a, pair<ll, int> b) { return min(a, b); },
                    [](ll a, ll b) { return b; });
    SegTree<ll> even(N, INFL,
                     [](pair<ll, int> a, pair<ll, int> b) { return min(a, b); },
                     [](ll a, ll b) { return b; });

    rep(i, N) {
        int p;
        cin >> p;
        if (i % 2 == 0) {
            even.change(i, p);
            odd.change(i, INFL);
        } else {
            even.change(i, INFL);
            odd.change(i, p);
        }
    }

    vi ans = solve(odd, even, N);
    rep(i, N) {
        cout << ans[i] << " ";
    }
    cout << endl;

    cout << endl;

    return 0;
}


Measured memory_bytes: 18860