// #pragma GCC target "prefer-vector-width=512"
// #pragma GCC optimize "Ofast"
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define rep(i,N) for(int i=0;i<(int)N;i++)
#define rrep(i,s,e) for(int i=s;i<(int)e;i++)
#define all(x) x.begin(),x.end()
#define vecin(N,A) rep(i,N) cin>>A[i]
#define vvecin(H,W,A) rep(i,H) rep(j,W) cin>>A[i][j]
int main(){
    int N;cin>>N;
    vector<int>P(N);
    vecin(N,P);
    vector<int>q;
    priority_queue<pair<int,int>,vector<pair<int,int>>,greater<pair<int,int>>>Q;
    map<int,pair<int,pair<int,int>>>M;
    vector<bool>seen(N,false);
    rep(i,N){
        M[i]={P[i],{i-1,i+1}};
    }
    rep(i,N-1){
        Q.push({P[i],i});
    }
    while(!Q.empty()){
        int val = Q.top().first;
        int ite = Q.top().second;
        Q.pop();
        if(seen[ite])continue;
        seen[ite]=true;
        q.push_back(val);
        int nit = M[ite].second.second;
        q.push_back(M[nit].first);
        seen[nit]=true;
        if(M[ite].second.first>=0)M[M[ite].second.first].second.second=M[nit].second.second;
        if(M[nit].second.second<N)M[M[nit].second.second].second.first=M[ite].second.first;
    }
    for(auto e :q)cout<<e<<" ";
    cout<<endl;
}