/* -*- coding: utf-8 -*-
 *
 * 2740.cc:  No.2740 Old Maid - yukicoder
 */

#include<cstdio>
#include<set>
#include<algorithm>
#include<utility>
 
using namespace std;

/* constant */

const int MAX_N = 200000;

/* typedef */

typedef pair<int,int> pii;
typedef set<pii> spii;

struct Node {
  int v, i;
  Node *prv, *nxt;
  Node(): v(), i(), prv(), nxt() {}
  Node(int _v, int _i): v(_v), i(_i), prv(), nxt() {}

  void remove() {
    if (prv != nullptr) prv->nxt = nxt;
    if (nxt != nullptr) nxt->prv = prv;
    prv = nxt = nullptr;
  }
};

/* global variables */

int ps[MAX_N], qs[MAX_N];
Node as[MAX_N];

/* subroutines */

/* main */

int main() {
  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%d", ps + i);

  spii ss;
  for (int i = 0; i < n; i++) {
    as[i].v = ps[i], as[i].i = i;
    if (i > 0) as[i].prv = &as[i - 1];
    if (i + 1 < n) as[i].nxt = &as[i + 1];
    ss.insert({ps[i], i});
  }

  int m = 0;
  for (int i = 0; i < n; i += 2) {
    int j = ss.begin()->second;
    ss.erase(ss.begin());
    if (as[j].nxt == nullptr) {
      j = ss.begin()->second;
      ss.erase(ss.begin());
    }

    ss.erase({as[j].nxt->v, as[j].nxt->i});
    qs[m++] = as[j].v, qs[m++] = as[j].nxt->v;
    as[j].nxt->remove();
    as[j].remove();
  }

  for (int i = 0; i < n; i++)
    printf("%d%c", qs[i], (i + 1 < n) ? ' ' : '\n');
  
  return 0;
}