#include <map>
#include <set>
#include <ctime>
#include <queue>
#include <stack>
#include <cmath>
#include <vector>
#include <bitset>
#include <cstdio>
#include <cctype>
#include <string>
#include <numeric>
#include <cstring>
#include <cassert>
#include <climits>
#include <cstdlib>
#include <iostream>
#include <algorithm>
#include <functional>
using namespace std ;
#define rep(i, a, b) for (int i = (a); i <= (b); i++)
#define per(i, a, b) for (int i = (a); i >= (b); i--)
#define loop(s, v, it) for (s::iterator it = v.begin(); it != v.end(); it++)
#define cont(i, x) for (int i = head[x]; i; i = e[i].nxt)
#define clr(a) memset(a, 0, sizeof(a))
#define ass(a, sum) memset(a, sum, sizeof(a))
#define lowbit(x) (x & -x)
#define all(x) x.begin(), x.end()
#define ub upper_bound
#define lb lower_bound
#define pq priority_queue
#define mp make_pair
#define pb push_back
#define pof pop_front
#define pob pop_back
#define fi first
#define se second
#define iv inline void
#define enter cout << endl
#define siz(x) ((int)x.size())
#define file(x) freopen(x".in", "r", stdin),freopen(x".out", "w", stdout)
typedef long long ll ;
typedef unsigned long long ull ;
typedef pair <int, int> pii ;
typedef vector <int> vi ;
typedef vector <pii> vii ;
typedef queue <int> qi ;
typedef queue <pii> qii ;
typedef set <int> si ;
typedef map <int, int> mii ;
typedef map <string, int> msi ;
const int N = 200010 ;
const int INF = 0x3f3f3f3f ;
const int iinf = 1 << 30 ;
const ll linf = 2e18 ;
const int MOD = 1000000007 ;
const double eps = 1e-7 ;
void douout(double x){ printf("%lf\n", x + 0.0000000001) ; }
template <class T> void print(T a) { cout << a << endl ; exit(0) ; }
template <class T> void chmin(T &a, T b) { if (a > b) a = b ; }
template <class T> void chmax(T &a, T b) { if (a < b) a = b ; }
template <class T> void upd(T &a, T b) { (a += b) %= MOD ; }
template <class T> void mul(T &a, T b) { a = (ll) a * b % MOD ; }

int p[N], f[N][20], Log[N] ;
int n ;

int min(int x, int y) {
    return p[x] < p[y] ? x : y ;
}

int find(int x, int y) {
    int z = Log[y - x + 1] ;
    return min(f[x][z], f[y - (1 << z) + 1][z]) ;
}

struct node {
    int l, r, x, y ;
    node (const int a = 0, const int b = 0) :
    l(a), r(b), x(find(a, b)), y(find(x + 1, b + 1)) {}
} ;

bool operator < (node a, node b) {
    return p[a.x] > p[b.x] ;
}

priority_queue <node> q ;

signed main(){
//	file("test") ;
    scanf("%d", &n) ;
    p[0] = n + 1 ;
    Log[0] = -1 ;
    rep(i, 1, n) {
        scanf("%d", &p[i]) ;
        f[i][0] = f[i][1] = i ;
        Log[i] = Log[i >> 1] + 1 ;
    }
    per(i, n, 1)
    for (int j = 2; i + (1 << j) - 1 <= n + 1; j++)
    f[i][j] = min(f[i][j - 1], f[i + (1 << (j - 1))][j - 1]) ;
    q.push((node) {1, n}) ;
    while (!q.empty()) {
        node a = q.top() ; q.pop() ;
        printf("%d %d ", p[a.x], p[a.y]) ;
        if (a.l < a.x) q.push((node) {a.l, a.x - 1}) ;
        if (a.x + 1 < a.y) q.push((node) {a.x + 1, a.y - 1}) ;
        if (a.y < a.r) q.push((node) {a.y + 1, a.r}) ;
    }
    enter ;
	return 0 ;
}

/*
写代码时请注意：
	1.ll？数组大小，边界？数据范围？
	2.精度？
	3.特判？
	4.至少做一些
思考提醒：
	1.最大值最小->二分？
	2.可以贪心么？不行dp可以么
	3.可以优化么
	4.维护区间用什么数据结构？
	5.统计方案是用dp？模了么？
	6.逆向思维？
*/




Measured memory_bytes: 19444