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

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int N; cin >> N;
    vector<bool> already(N);
    vector<int> P(N),rev(N),answer,fro(N,-1),bac(N,-1);
    for(int i=0; i<N; i++){
        int p; cin >> p; p--;
        rev.at(p) = i; P.at(i) = p;
    }
    for(int i=1; i<N; i++) bac.at(i) = i-1;
    for(int i=0; i<N-1; i++) fro.at(i) = i+1;

    for(int i=0; i<N; i++){
        if(already.at(i)) continue;
        int pos = rev.at(i);
        if(fro.at(pos) == -1) continue;
        answer.push_back(P.at(pos));
        answer.push_back(P.at(fro.at(pos)));
        already.at(P.at(pos)) = true;
        already.at(P.at(fro.at(pos))) = true;
        int one = bac.at(pos),two = pos,three = fro.at(pos),four = fro.at(fro.at(pos));
        if(one == -1 && four == -1){}
        else if(one == -1){bac.at(four) = -1;}
        else if(four == -1){fro.at(one) = -1;}
        else{bac.at(four) = one; fro.at(one) = four;}  
    }
    for(auto &a : answer) cout << a+1 << " "; cout << endl;
    
}