#include <algorithm>
#include <bitset>
#include <climits>
#include <cmath>
#include <cstdio>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>

#define MOD 1000000007
#define MOD2 998244353
#define int long long
#define double long double
#define EPS 1e-9
//#define PI 3.14159265358979

#define rep(i, n) for (int i = 0; i < (int)(n); i++)

using namespace std;

template < typename T >
ostream &operator<<(ostream &os, const vector< T > &A) {
	for (int i = 0; i < A.size(); i++)
		os << A[i] << " ";
	os << endl;
	return os;
}
template <>
ostream &operator<<(ostream &os, const vector< vector< int > > &A) {
	int N = A.size();
	for (int i = 0; i < N; i++) {
		for (int j = 0; j < A[i].size(); j++)
			os << A[i][j] << " ";
		os << endl;
	}
	return os;
}
template < typename T, typename U >
ostream &operator<<(ostream &os, const pair< T, U > &p) {
	os << "(" << p.first << "," << p.second << ")";
	return os;
}
template < typename T, typename U >
istream &operator>>(istream &is, pair< T, U > &p) {
	is >> p.first >> p.second;
	return is;
}
template < typename T >
istream &operator>>(istream &is, vector< T > &A) {
	rep(i, A.size()) is >> A[i];
	return is;
}

typedef pair< int, int > pii;
typedef long long ll;

struct edge {
	int from, to, d, c, i;
	edge(int _from = 0, int _to = 0, int _d = 0, int _c = 0) {
		from = _from;
		to = _to;
		d = _d;
		c = _c;
	}
	bool operator<(const edge &rhs) const {
		return (d == rhs.d) ? (c < rhs.c) : (d < rhs.d);
	}
};
struct aabb {
	int x1, y1, x2, y2;
	aabb(int x1, int y1, int x2, int y2) : x1(x1), y1(y1), x2(x2), y2(y2) {}
};

typedef vector< edge > edges;
typedef vector< edges > graph;
struct flow {
	int to, cap, rev, cost;
	flow(int to = 0, int cap = 0, int rev = 0, int cost = 0) : to(to), cap(cap), rev(rev), cost(cost) {}
};
typedef vector< vector< flow > > flows;

const int di[4] = {0, -1, 0, 1};
const int dj[4] = {-1, 0, 1, 0};
const int ci[5] = {0, 0, -1, 0, 1};
const int cj[5] = {0, -1, 0, 1, 0};
const ll LINF = LLONG_MAX / 2;
const int INF = INT_MAX / 2;
const double PI = acos(-1);

int pow2(int n) { return 1LL << n; }
template < typename T, typename U >
bool chmin(T &x, const U &y) {
	if (x > y) {
		x = y;
		return true;
	}
	return false;
}
template < typename T, typename U >
bool chmax(T &x, const U &y) {
	if (x < y) {
		x = y;
		return true;
	}
	return false;
}

template < typename A, size_t N, typename T >
void Fill(A (&array)[N], const T &val) {
	fill((T *)array, (T *)(array + N), val);
}
struct initializer {
	initializer() {
		cout << fixed << setprecision(20);
	}
};
initializer _____;
template < class Monoid >
struct SegTmax {
	//to be set--------------------------------------------------
	const static Monoid UNITY = -LINF; //UNITY=0
	Monoid merge(const Monoid &a, const Monoid &b) {
		return max(a, b); //a+b;
	}
	//kokomade----------------------------------------------------
	struct node {
		int l2, r2, k;
		inline bool leaf() {
			return l2 + 1 == r2;
		}
		pair< node, node > childs() {
			node hidari(l2, mid(), left()), migi(mid(), r2, right());
			return make_pair(hidari, migi);
		}
		node(int _l2, int _r2, int _k) : l2(_l2), r2(_r2), k(_k) {}
		node() {
		}

	private:
		inline int left() {
			return 2 * k + 1;
		}
		inline int right() {
			return 2 * k + 2;
		}
		inline int mid() {
			return (l2 + r2) / 2;
		}
	};
	vector< Monoid > A;
	int n;
	void update(int k, Monoid x) {
		int kk = k + n - 1;
		A[kk] = x;
		while (kk > 0) {
			kk = (kk - 1) / 2;
			A[kk] = merge(A[2 * kk + 1], A[2 * kk + 2]);
		}
	}
	Monoid get(int l, int r, node &o) {
		//sotogawa
		if (o.r2 <= l || r <= o.l2)
			return UNITY;
		//uchigawa
		if (l <= o.l2 && o.r2 <= r)
			return A[o.k];
		//sonota
		auto c = o.childs();
		Monoid vl = get(l, r, c.first);
		Monoid vr = get(l, r, c.second);

		return merge(vl, vr);
	}
	Monoid get(int l, int r) {
		node o(0, n, 0);
		return get(l, r, o);
	}
	void init(vector< Monoid > &B) {
		n = 1;
		while (n < B.size())
			n <<= 1;
		A = vector< Monoid >(2 * n - 1, 0);
		for (int i = 0; i < B.size(); i++)
			A[i + n - 1] = B[i];
		for (int k = n - 2; k >= 0; k--) {
			A[k] = merge(A[2 * k + 1], A[2 * k + 2]);
		}
	}
	SegTmax(vector< Monoid > &B) {
		init(B);
	}
	SegTmax(int _n) {
		vector< Monoid > B(_n, UNITY);
		init(B);
	}
};
template < class Monoid >
struct SegTmin {
	//to be set--------------------------------------------------
	constexpr static inline Monoid UNITY = make_pair(LINF, LINF); //UNITY=0
	Monoid merge(const Monoid &a, const Monoid &b) {
		return min(a, b); //a+b;
	}
	//kokomade----------------------------------------------------
	struct node {
		int l2, r2, k;
		inline bool leaf() {
			return l2 + 1 == r2;
		}
		pair< node, node > childs() {
			node hidari(l2, mid(), left()), migi(mid(), r2, right());
			return make_pair(hidari, migi);
		}
		node(int _l2, int _r2, int _k) : l2(_l2), r2(_r2), k(_k) {}
		node() {
		}

	private:
		inline int left() {
			return 2 * k + 1;
		}
		inline int right() {
			return 2 * k + 2;
		}
		inline int mid() {
			return (l2 + r2) / 2;
		}
	};
	vector< Monoid > A;
	int n;
	void update(int k, Monoid x) {
		int kk = k + n - 1;
		A[kk] = x;
		while (kk > 0) {
			kk = (kk - 1) / 2;
			A[kk] = merge(A[2 * kk + 1], A[2 * kk + 2]);
		}
	}
	Monoid get(int l, int r, node &o) {
		//sotogawa
		if (o.r2 <= l || r <= o.l2)
			return UNITY;
		//uchigawa
		if (l <= o.l2 && o.r2 <= r)
			return A[o.k];
		//sonota
		auto c = o.childs();
		Monoid vl = get(l, r, c.first);
		Monoid vr = get(l, r, c.second);

		return merge(vl, vr);
	}
	Monoid get(int l, int r) {
		node o(0, n, 0);
		return get(l, r, o);
	}
	void init(vector< Monoid > &B) {
		n = 1;
		while (n < B.size())
			n <<= 1;
		A = vector< Monoid >(2 * n - 1, UNITY);
		for (int i = 0; i < B.size(); i++)
			A[i + n - 1] = B[i];
		for (int k = n - 2; k >= 0; k--) {
			A[k] = merge(A[2 * k + 1], A[2 * k + 2]);
		}
	}
	SegTmin(vector< Monoid > &B) {
		init(B);
	}
	SegTmin(int _n) {
		vector< Monoid > B(_n, UNITY);
		init(B);
	}
};
int N, M, K, T, Q, H, W;
signed main() {
	cin >> N;
	vector< int > P(N);
	cin >> P;
	SegTmin< pii > evenmin(N);
	SegTmin< pii > oddmin(N);
	rep(i, N) {
		if (i % 2 == 0) {
			evenmin.update(i, make_pair(P[i], i));
		} else {
			oddmin.update(i, make_pair(P[i], i));
		}
	}
	priority_queue< tuple< pii, int, int >, vector< tuple< pii, int, int > >, greater< tuple< pii, int, int > > > q;
	q.push(make_tuple(evenmin.get(0, N), 0, N));
	vector< int > ans(N);
	int k = 0;
	while (!q.empty()) {
		auto t = q.top();
		q.pop();
		pii p;
		int l, r;
		tie(p, l, r) = t;
		pii e;
		if (l % 2 == 0)
			e = oddmin.get(p.second, r);
		else
			e = evenmin.get(p.second, r);
		ans[k++] = p.first;
		ans[k++] = e.first;
		auto f = [&q, &evenmin, &oddmin](int l, int r) {
			if (l < r) {
				pii p;
				if (l % 2 == 0)
					p = evenmin.get(l, r);
				else
					p = oddmin.get(l, r);
				q.emplace(p, l, r);
			}
		};
		f(l, p.second);
		f(p.second + 1, e.second);
		f(e.second + 1, r);
	}
	cout << ans;
	return 0;
}

Measured memory_bytes: 25956