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

#define FOR(i, l, r) for(ll i = l; i < r; i++)
#define rep(i, n) FOR(i, 0, n)
#define FORR(i, l, r) for(ll i = r - 1; i >= l; i--)
#define ALL(ar) begin(ar), end(ar)

template <typename T1, typename T2>
inline bool chmax(T1 &a, T2 b) {
    return a < b && (a = b, true);
}
template <typename T1, typename T2>
inline bool chmin(T1 &a, T2 b) {
    return a > b && (a = b, true);
}
template <typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) {
    is >> p.first >> p.second;
    return is;
}
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
    os << p.first << ' ' << p.second;
    return os;
}
template <typename T>
istream &operator>>(istream &is, vector<T> &v) {
    for(T &x : v) is >> x;
    return is;
}
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
    for(size_t i = 0; i < v.size(); i++) os << (i ? " " : "") << v[i];
    return os;
}
//-------------------------------------------------

void solve() {
    int n;
    cin >> n;
    vector<int> p(n);
    cin >> p;
    set<int> st;
    map<int, int> pos;
    rep(i, n) st.insert(i);
    rep(i, n) {
        p[i]--;
        pos[p[i]] = i;
    }

    vector<int> q;
    rep(i, n / 2) {
        auto mn = pos.begin();
        auto nxt = st.upper_bound(mn->second);
        if(nxt == st.end()) {
            mn++;
            nxt = st.upper_bound(mn->second);
        }

        q.push_back(mn->first + 1);
        q.push_back(p[*nxt] + 1);
        pos.erase(p[*nxt]);
        st.erase(nxt);
        st.erase(mn->second);
        pos.erase(mn);
    }

    cout << q << endl;
}

int main() {
    int t = 1;
    // cin >> t;
    while(t--) solve();
}