/*input
4
3 2 4 1
*/
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

#define int long long 
#define double long double
#define f first
#define s second
#define mp make_pair
#define pb push_back

#define RE(i,n) for (int i = 1; i <= n; i++)
#define RED(i,n) for (int i = n; i > 0; i--)
#define REPS(i,n) for(int i = 1; (i*i) <= n; i++)
#define REP(i,n) for (int i = 0; i < (int)n; i++)
#define FOR(i,a,b) for (int i = a; i < b; i++)
#define REPD(i,n) for (int i = n-1; i >= 0; i--)
#define FORD(i,a,b) for (int i = a; i >= b; i--)

#define all(v) v.begin(),v.end()
#define pii pair<int,int>
#define vi vector<int>
#define vvi vector<vi>
#define print(arr) for (auto it = arr.begin(); it != arr.end(); ++it) cout << *it << " "; cout << endl;
#define debug(x) cout << x << endl;
#define debug2(x,y) cout << x << " " << y << endl;
#define debug3(x,y,z) cout << x << " " << y << " " << z << endl;

typedef tree<
int,
null_type,
less<int>,
rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;

const int INF = 1e18+1;
const int MOD = 1e9+7;
const double PI = 3.14159265358979323846264338;

int raise(int a,int n,int m = MOD){
  if(n == 0)return 1;
  if(n == 1)return a;
  int x = 1;
    x *= raise(a,n/2,m);
    x %= m;
    x *= x;
    x %= m;
    if(n%2)x*= a;
    x %= m;
    return x;
}

int floor1(int n,int k){
    if(n%k == 0 || n >= 0)return n/k;
    return (n/k)-1;
}

int ceil1(int n,int k){
    return floor1(n+k-1,k);
}

const int N = 2e5+1;
int a[N];
pair<int,int> seg[4*N][2];//0 for even indices
int n;
int currentnode = 0;
vector<int> adj[N];
pair<int,int> ans[N];

#define child 2*node
#define mid (l+r)/2

void build(int idx,int node,int l,int r){
	if(l == r){
		if(idx%2 == l%2){
			seg[node][idx] = {a[l],l};
		}
		else{
			seg[node][idx] = {INF,0};
		}
		return;
	}
	build(idx,child,l,mid);
	build(idx,child+1,mid+1,r);
	seg[node][idx] = min(seg[child][idx],seg[child+1][idx]);
}

pair<int,int> query(int idx,int node,int l,int r,int start,int end){
	if(l > end or start > r)return {INF,0};
	if(start <= l and r <= end)return seg[node][idx];
	return min(query(idx,child,l,mid,start,end),query(idx,child+1,mid+1,r,start,end));
}

void recur(int l,int r,int parent){
	
	if(l > r)return;
	int here = ++currentnode;
    //cout << l <<  " " << r << " " <<currentnode << endl;
	if(currentnode != 1){
		adj[parent].pb(currentnode);
		adj[currentnode].pb(parent);
	}
	int idxmin = query(l%2,1,1,n,l,r).s;
	int secondidx = query(!(l%2),1,1,n,idxmin+1,r).s;
	//cout << idxmin << " " << secondidx << endl;
	ans[currentnode] = {a[idxmin],a[secondidx]};
	recur(l,idxmin-1,here);
	recur(idxmin+1,secondidx-1,here);
	recur(secondidx+1,r,here);
}

vector<int> answer;
bool vis[N];

void bfs(){
	priority_queue< pair<int,int> > pq;
	pq.push({-ans[1].f,1});
	vis[1] = 1;
	while(!pq.empty()){
		int u = pq.top().s;
		answer.pb(u);
	//	cout << "POPIN " << u << endl;
		pq.pop();
		for(int v:adj[u]){
			if(vis[v])continue;
			vis[v] = 1;
	//		cout << " PUSHIN " << v << endl;
			pq.push({-ans[v].f,v});
		}
	}
	for(auto hehe:answer){
		cout << ans[hehe].f << " " << ans[hehe].s << " ";
	}
}

void solve(){
  	cin >> n;
  	RE(i,n){
  		cin >> a[i];
  	}
  	build(0,1,1,n);
  	build(1,1,1,n);
  	recur(1,n,0);
  	bfs();
}

signed main(){
  ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
  //freopen(".in","r",stdin);freopen(".out","w",stdout);
  int t = 1;
  //cin >> t;
  while(t--){
    solve();
  }
  return 0;
}

Measured memory_bytes: 37620