#include <bits/stdc++.h>
#include <atcoder/all>
using mint = atcoder::modint998244353;
//using mint = atcoder::modint1000000007;
using namespace atcoder;
using namespace std;

using ll = long long;
using pi = pair<int,int>;
using pl = pair<ll,ll>;
using vi = vector<int>;
using vm = vector<mint>;
using vvi = vector<vi>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vpi = vector<pair<int,int>>;
using vpl = vector<pair<ll,ll>>;
#define rep(i,n) for (ll i = 0; i < n; i++)
#define replr(i,l,r) for (ll i = l; i < r; i++)
set<char> abc = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
const int inf =1e9;
const ll infl = 4e18;

template <typename T>
bool chmax(T &a, const T& b) {if (a < b) {a = b;  return true;}return false;}
template <typename T>
bool chmin(T &a, const T& b) {if (a > b) {a = b;  return true;}return false;}
template <typename T>
T max(vector<T> &v) {T m = 0;for (auto x : v) chmax(m, x);return m;}
template <typename T>
T min(vector<T> &v) {T m = inf;for (auto x : v) chmin(m, x);return m;}
template <typename T>
void print(vector<T> &v){for(auto x : v){cout<<x<<' ';}cout<<'\n';}
/*memo
一番若いものを選び続ける
*/


int main(){
    int N; cin >> N;
    vi p(N);rep(i,N) cin >> p[i];
    vi pos(N);
    vi nex(N,-1);
    vi pre(N,-1);
    rep(i,N-1) nex[i] =i+1;
    replr(i,1,N) pre[i] = i-1;
    rep(i,N) pos[p[i]-1] = i;
    vi q;
    rep(i,N){
        int x=pos[i];
        if (p[x]==-1) continue;
        if (nex[x]==-1) continue;
        q.push_back(p[x]);
        q.push_back(p[nex[x]]);
        if (pre[x]!=-1) nex[pre[x]]=nex[nex[x]];
        if (nex[nex[x]]!=-1) pre[nex[nex[x]]]=pre[x];
        p[x]=-1;
        p[nex[x]]=-1;
    }
    print(q);
}