// includes
#include <bits/stdc++.h>
using namespace std;

// macros
#define pb emplace_back
#define mk make_pair
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define rep(i, n) FOR(i, 0, n)
#define rrep(i, n) for(int i=((int)(n)-1);i>=0;i--)
#define irep(itr, st) for(auto itr = (st).begin(); itr != (st).end(); ++itr)
#define irrep(itr, st) for(auto itr = (st).rbegin(); itr != (st).rend(); ++itr)
#define whole(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end())
#define bit(n) (1LL<<(n))
// functions
template <class T>bool chmax(T &a, const T &b){if(a < b){a = b; return 1;} return 0;}
template <class T>bool chmin(T &a, const T &b){if(a > b){a = b; return 1;} return 0;}
template <typename T> istream &operator>>(istream &is, vector<T> &vec){for(auto &v: vec)is >> v; return is;}
template <typename T> ostream &operator<<(ostream &os, const vector<T>& vec){for(int i = 0; i < vec.size(); i++){ os << vec[i]; if(i + 1 != vec.size())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const set<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const unordered_set<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const multiset<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const unordered_multiset<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p){os << p.first << " " << p.second; return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const map<T1, T2> &mp){for(auto itr = mp.begin(); itr != mp.end(); ++itr){ os << itr->first << ":" << itr->second; auto titr = itr; if(++titr != mp.end())os << " "; } return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const unordered_map<T1, T2> &mp){for(auto itr = mp.begin(); itr != mp.end(); ++itr){ os << itr->first << ":" << itr->second; auto titr = itr; if(++titr != mp.end())os << " "; } return os;}
//  types
using ll = long long int;
using P = pair<int, int>;
// constants
const int inf = 1e9;
const ll linf = 1LL << 50;
const double EPS = 1e-10;
const int mod = 1000000007;
const int dx[4] = {-1, 0, 1, 0};
const int dy[4] = {0, -1, 0, 1};
// io
struct fast_io{
  fast_io(){ios_base::sync_with_stdio(false); cin.tie(0); cout << fixed << setprecision(20);}
} fast_io_;

template<typename T, typename E>
struct SegmentTree_ {
  function<T(T, T)> f; // aggregate function
  function<T(T, E)> g; // update function
  int n;
  T def;
  vector<T> vec;
  SegmentTree_(){}
  SegmentTree_(int n_, function<T(T, T)> f, function<T(T, E)> g, T def, vector<T> v=vector<T>()): f(f), g(g), def(def){

    // initialize vector
    n = 1;
    while(n < n_){
      n *= 2;
    }
    vec = vector<T>(2*n -1, def);

    // initialize segment tree
    for(int i = 0; i < v.size(); i++){
      vec[i + n - 1] = v[i];
    }
    for(int i = n - 2; i >= 0; i--){
      vec[i] = f(vec[2*i+1], vec[2*i+2]);
    }
  }
  void update(int k, const E &val){
    k = k + n - 1;
    vec[k] = g(vec[k], val);
    while(k > 0){
      k = (k - 1) / 2;
      vec[k] = f(vec[2*k+1], vec[2*k+2]);
    }
  }
  // [l, r) -> [a, b) (at k)
  T query(int a, int b, int k, int l, int r){
    if(r <= a || b <= l)return def;
    if(a <= l && r <= b)return vec[k];
    T ld = query(a, b, 2*k+1, l, (l+r)/2);
    T rd = query(a, b, 2*k+2, (l+r)/2, r);
    return f(ld, rd);
  }
  T query(int a, int b){
    return query(a, b, 0, 0, n);
  }
};

template<typename T, typename E>
using SegmentTree = struct SegmentTree_<T, E>;
using SegmentTreeI = SegmentTree<int, int>;
using SegmentTreeL = SegmentTree<long long, long long>;

SegmentTree<P, P> seg[2];

int p[200010];
int n;

int main(int argc, char const* argv[])
{
  cin >> n;
  rep(i, n)cin >> p[i], p[i]--;
  vector<P> pv0(n, mk(inf, inf)), pv1(n, mk(inf, inf));
  rep(i, n){
    if(i & 1)pv1[i] = mk(p[i], i);
    else pv0[i] = mk(p[i], i);
  }
  seg[0] = SegmentTree<P, P>(n, [](P a, P b){return min(a, b);},
                                  [](P a, P b){return b;}, mk(inf, inf), pv0);
  seg[1] = SegmentTree<P, P>(n, [](P a, P b){return min(a, b);},
                                  [](P a, P b){return b;}, mk(inf, inf), pv1);
  
  auto find = [&](int l, int r) -> pair<P, P>{
    auto p = seg[l&1].query(l, r - 1);
    int m = p.second;
    auto p2 = seg[(1-l&1)].query(m+1, r);
    int m2 = p2.second;
    return mk(mk(p.first, p2.first), (mk(m, m2)));
  };
  // (first, second), [l, r)
  using PPP = pair<pair<P, P>, P>;
  priority_queue<PPP, vector<PPP>, greater<PPP>> pq;
  pq.push(mk(find(0, n), mk(0, n)));
  vector<int> res; res.reserve(n);
  while(!pq.empty()){
    auto q = pq.top(); pq.pop();
    auto q1 = q.first.first, q2 = q.first.second;
    res.pb(q1.first); res.pb(q1.second);
    int l[3], r[3];
    l[0] = q.second.first, r[0] = q2.first;
    l[1] = q2.first + 1, r[1] = q2.second;
    l[2] = q2.second + 1, r[2] = q.second.second;
    rep(i, 3){
      if(l[i] >= r[i])continue;
      pq.push(mk(find(l[i], r[i]), mk(l[i], r[i])));
    }
  }
  rep(i, n)res[i]++;
  cout << res << endl;
  return 0;
}


Measured memory_bytes: 16868