#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <functional>
#include <set>
#include <ctime>
#include <random>
#include <chrono>
#include <cassert>
#include <tuple>
#include <utility>
using namespace std;

namespace {
  using Integer = long long; //__int128;
  template<class T, class S> istream& operator >> (istream& is, pair<T,S>& p){return is >> p.first >> p.second;}
  template<class T> istream& operator >> (istream& is, vector<T>& vec){for(T& val: vec) is >> val; return is;}
  template<class T> istream& operator ,  (istream& is, T& val){ return is >> val;}
  template<class T, class S> ostream& operator << (ostream& os, const pair<T,S>& p){return os << p.first << " " << p.second;}
  template<class T> ostream& operator << (ostream& os, const vector<T>& vec){for(size_t i=0; i<vec.size(); i++) os << vec[i] << (i==vec.size()-1?"":" "); return os;}
  template<class T> ostream& operator ,  (ostream& os, const T& val){ return os << " " << val;}

  template<class H> void print(const H& head){ cout << head; }
  template<class H, class ... T> void print(const H& head, const T& ... tail){ cout << head << " "; print(tail...); }
  template<class ... T> void println(const T& ... values){ print(values...); cout << endl; }

  template<class H> void eprint(const H& head){ cerr << head; }
  template<class H, class ... T> void eprint(const H& head, const T& ... tail){ cerr << head << " "; eprint(tail...); }
  template<class ... T> void eprintln(const T& ... values){ eprint(values...); cerr << endl; }

  class range{ Integer start_, end_, step_; public: struct range_iterator{ Integer val, step_; range_iterator(Integer v, Integer step) : val(v), step_(step) {} Integer operator * (){return val;} void operator ++ (){val += step_;} bool operator != (range_iterator& x){return step_ > 0 ? val < x.val : val > x.val;} }; range(Integer len) : start_(0), end_(len), step_(1) {} range(Integer start, Integer end) : start_(start), end_(end), step_(1) {} range(Integer start, Integer end, Integer step) : start_(start), end_(end), step_(step) {} range_iterator begin(){ return range_iterator(start_, step_); } range_iterator   end(){ return range_iterator(  end_, step_); } };

  inline string operator "" _s (const char* str, size_t size){ return move(string(str)); }
  constexpr Integer my_pow(Integer x, Integer k, Integer z=1){return k==0 ? z : k==1 ? z*x : (k&1) ? my_pow(x*x,k>>1,z*x) : my_pow(x*x,k>>1,z);}
  constexpr Integer my_pow_mod(Integer x, Integer k, Integer M, Integer z=1){return k==0 ? z%M : k==1 ? z*x%M : (k&1) ? my_pow_mod(x*x%M,k>>1,M,z*x%M) : my_pow_mod(x*x%M,k>>1,M,z);}
  constexpr unsigned long long operator "" _ten (unsigned long long value){ return my_pow(10,value); }

  inline int k_bit(Integer x, int k){return (x>>k)&1;} //0-indexed

  mt19937 mt(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count());

  template<class T> string join(const vector<T>& v, const string& sep){ stringstream ss; for(size_t i=0; i<v.size(); i++){ if(i>0) ss << sep; ss << v[i]; } return ss.str(); }

  inline string operator * (string s, int k){ string ret; while(k){ if(k&1) ret += s; s += s; k >>= 1; } return ret; }
}
constexpr long long mod = 9_ten + 7;


template<class Value = int>
class SegmentTree{
  int n;
  vector<Value> V;
  Value DEFAULT_VALUE;

  //evaluation function
  static Value default_evaluate(Value a, Value b){
    return min(a,b);
  }

  function< Value(Value, Value) > evaluate;

  //return evaluated value in [a,b)
  //T[at] covers [l,r)
  Value RangeEvaluation(int a, int b, int at, int l, int r){
    //out of range
    if(r <= a || b <= l) return DEFAULT_VALUE;
    //covered
    if(a <= l && r <= b) return V[at];

    //partially covered
    else{
      Value val_left = RangeEvaluation(a,b, at*2+1, l, (l+r)/2);
      Value val_right = RangeEvaluation(a,b, at*2+2, (l+r)/2, r);
      return evaluate(val_left, val_right);
    }
  }

 public:
  SegmentTree(int size, Value DEFAULT = 1e7, function< Value(Value, Value) > eval = default_evaluate){
    DEFAULT_VALUE = DEFAULT;
    evaluate = eval;
    n=1;
    while(n<size) n <<= 1;
    V = vector<Value>(2*n - 1, DEFAULT_VALUE);
  }

  void update(int at, Value new_val){
    at += n-1;
    V[at] = new_val;
    while(at>0){
      at = (at-1)/2;
      V[at] = evaluate(V[at*2 + 1], V[at*2 + 2]);
    }
  }


  //return evaluated value in [l,r)
  Value RangeEvaluation(int l, int r){
    if(l>=r) return DEFAULT_VALUE;
    if(l>=n) return DEFAULT_VALUE;
    return RangeEvaluation(l,r, 0, 0, n);
  }
};



int main(){
  int n;
  cin >> n;
  vector<int> p(n);
  cin >> p;

  vector<int> pos(n);
  for(int i=0; i<n; i++){
    pos[p[i]-1] = i;
  }

  SegmentTree<int> even(n/2+1), odd(n/2+1);
  for(int i=0; i<n; i++){
    if(i&1){
      odd.update(i/2, p[i]);
    }else{
      even.update(i/2, p[i]);
    }
  }

  int m = n/2;

  vector<pair<int,int>> ans;
  priority_queue<pair<int,pair<int,int>>, vector<pair<int,pair<int,int>>>, greater<pair<int,pair<int,int>>>> pq;

  pq.push( {even.RangeEvaluation(0,n/2), {0,n}} );
  while(pq.size()){
    auto p = pq.top();
    pq.pop();
    int l = p.second.first;
    int r = p.second.second;

    int x = -1;
    int y = -1;
    if(l&1){
      x = odd.RangeEvaluation(l/2, r/2);
    }else{
      x = even.RangeEvaluation(l/2, r/2);
    }
    if(l&1){
      y = even.RangeEvaluation((pos[x-1]+1)/2, (r+1)/2);
    }else{
      y = odd.RangeEvaluation(pos[x-1]/2, r/2);
    }

    ans.push_back( {x,y} );

    int x_pos = pos[x-1];
    int y_pos = pos[y-1];

    if( x_pos&1 ){
      odd.update(x_pos/2, 1e7);
    }else{
      even.update(x_pos/2, 1e7);
    }
    if( y_pos&1 ){
      odd.update(y_pos/2, 1e7);
    }else{
      even.update(y_pos/2, 1e7);
    }

    if( l < x_pos ){
      int val;
      if(l&1){
        val = odd.RangeEvaluation(l/2, x_pos/2);
      }else{
        val = even.RangeEvaluation(l/2, x_pos/2);
      }
      pq.push( {val, {l, x_pos}} );
    }

    if( y_pos - x_pos >= 2 ){
      int val;
      if( (x_pos+1)&1 ){
        val = odd.RangeEvaluation((x_pos+1)/2, y_pos/2);
      }else{
        val = even.RangeEvaluation((x_pos+1)/2, y_pos/2);
      }
      pq.push( {val, {x_pos+1, y_pos}} );
    }

    if( y_pos < r-1 ){
      int val;
      if( (y_pos+1)&1 ){
        val = odd.RangeEvaluation((y_pos+1)/2, r/2);
      }else{
        val = even.RangeEvaluation((y_pos+1)/2, r/2);
      }
      pq.push( {val, {y_pos+1, r}});
    }
  }

  println(join(ans, " "));

  return 0;
}


Measured memory_bytes: 7824