#include <algorithm>
#include <iostream>
#include <cstdio>
#include <map>
#include <numeric>
#include <cmath>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <complex>
#include <string.h>
#include <unordered_set>
#include <unordered_map>
#include <bitset>
#include <iomanip>
#include <sys/time.h>
#include <tuple>
#include <random>
using namespace std;

#define endl '\n'
#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
#define UNIQ(v) (v).erase(unique((v).begin(), (v).end()), (v).end())

typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;
typedef complex<double> comp;
typedef vector< vector<ld> > matrix;
struct pairhash {
public:
    template<typename T, typename U>
    size_t operator()(const pair<T, U> &x) const {
	size_t seed = hash<T>()(x.first);
	return hash<U>()(x.second) + 0x9e3779b9 + (seed<<6) + (seed>>2);
    }
};
const int inf = 1e9 + 9;
const ll mod = 1e9 + 7;
const double eps = 1e-8;
const double pi = acos(-1);

int n;
int p[200100];

template<typename T>
class SegmentTree {
    class Node {
    public:
        ll l, r;
        T data;
        Node* child_L;
        Node* child_R;
        Node(ll l, ll r, T data) {
            this->l = l;
            this->r = r;
            this->data = data;
            this->child_L = nullptr;
            this->child_R = nullptr;
        }
    };

    Node* root;
    ll N;
    const T init = inf;
    T op(const T& a, const T& b) {
        return min(a, b);
    }
public:
    SegmentTree(ll n) {
        this->N = n;
        this->root = new Node(0, n, init);
    }

    void update(Node* node, ll k, T a) {
        if (node->l <= k && k < node->r) {
            if (node->l == k && node->r == k+1) {
                node->data = a;
            } else {
                if (node->child_L == nullptr) {
                    ll mid = (node->l + node->r) / 2;
                    node->child_L = new Node(node->l, mid, init);
                    node->child_R = new Node(mid, node->r, init);
                }
                update(node->child_L, k, a);
                update(node->child_R, k, a);
                node->data = op(node->child_L->data, node->child_R->data);
            }
        }
    }
    void update(ll k, T a) {
        update(this->root, k, a);
    }

    void add(Node* node, ll k, T a) {
        if (node->l <= k && k < node->r) {
            if (node->l == k && node->r == k+1) {
                node->data += a;
            } else {
                if (node->child_L == nullptr) {
                    ll mid = (node->l + node->r) / 2;
                    node->child_L = new Node(node->l, mid, init);
                    node->child_R = new Node(mid, node->r, init);
                }
                add(node->child_L, k, a);
                add(node->child_R, k, a);
                node->data = op(node->child_L->data, node->child_R->data);
            }
        }
    }
    void add(ll k, T a) {
        add(this->root, k, a);
    }

    T query(Node* node, ll l, ll r) {
        if (node == nullptr || node->r <= l || r <= node->l) return init;
        if (l <= node->l && node->r <= r) return node->data;
        return op(query(node->child_L, l, r), query(node->child_R, l, r));
    }
    
    T query(ll l, ll r) {
        return query(this->root, l, r);
    }

    T get(ll i) {
        return query(this->root, i, i+1);
    }
};

SegmentTree<int> even(200100);
SegmentTree<int> odd(200100);

struct S {
    int l, r;
    int idx_l, idx_r;
    int v0, v1;
    bool operator>(const S &a) const {
        return v0 > a.v0;
    }
};

int rev[200100];

S calc(int l, int r) {
    int a, b, idx_l, idx_r;
    if (l % 2 == 0) {
        a = even.query(l, r);
        idx_l = rev[a];
        b = odd.query(idx_l, r);
        idx_r = rev[b];
    } else {
        a = odd.query(l, r);
        idx_l = rev[a];
        b = even.query(idx_l, r);
        idx_r = rev[b];
    }
    S s;
    s.l = l; s.r = r;
    s.idx_l = idx_l; s.idx_r = idx_r;
    s.v0 = a; s.v1 = b;
    return s;
}

void solve() {
    for (int i = 0; i < n; i++) {
        if (i % 2 == 0) {
            even.update(i, p[i]);
        } else {
            odd.update(i, p[i]);
        }
        rev[p[i]] = i;
    }

    vector<int> res;
    priority_queue<S, vector<S>, greater<S> > que;
    que.push(calc(0, n));
    while (!que.empty()) {
        S seg = que.top(); que.pop();
        res.push_back(seg.v0);
        res.push_back(seg.v1);
        if (seg.idx_l - seg.l > 1) que.push(calc(seg.l, seg.idx_l));
        if (seg.idx_r - (seg.idx_l+1) > 1) que.push(calc(seg.idx_l+1, seg.idx_r));
        if (seg.r - (seg.idx_r+1) > 1) que.push(calc(seg.idx_r+1, seg.r));
    }

    for (int i = 0; i < n; i++) {
        cout << res[i];
        if (i < n-1) cout << " ";
        else cout << endl;
    }
}

void input() {
    cin >> n;
    for (int i = 0; i < n; i++) cin >> p[i];
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(15);

    input();
    solve();
}


Measured memory_bytes: 43316