#include <bits/stdc++.h>
#define NMax 100100
#define Min(a, b) (a < b) ? a : b
#define INF 0x3f3f3f3f

using namespace std;

int N, M, pare[4*NMax], impare[4 * NMax], i, Minim1, Minim2, poz, val, start, sfarsit, tip, a, b, x, Minim, app_on_pos[NMax];
void Update (int nod, int st, int dr, int ARB[])
{
    if(st == dr)
    {
        ARB[nod] = val;
        return;
    }
    int m = (st + dr) / 2;
    if(poz <= m) Update(2 * nod, st, m, ARB);
    else Update(2 * nod + 1,m + 1, dr, ARB);
    ARB[nod] = Min(ARB[2 * nod], ARB[2 * nod + 1]);
}
void Interog (int nod, int st, int dr, int ARB[])
{
    if(start<=st && dr<=sfarsit)
    {
        if(Minim > ARB[nod]) {
            Minim = ARB[nod];
        }
        return;
    }
    int m = (st + dr) / 2;
    if(start <= m) Interog(2 * nod, st, m, ARB);
    if(m < sfarsit) Interog(2 * nod +1 ,m + 1, dr, ARB);
}
int main()
{
    cin >> N;

    for (int i = 1; i <= N; i++) {
        cin >> x;
        val = x;
        if (i % 2 == 0) {
            poz = i / 2;
            Update(1, 1, N / 2, pare);
        } else {
            poz = i / 2 + 1;
            Update(1, 1, N / 2, impare);
        }
        app_on_pos[x] = poz;
    }

    for (int i = 1; i <= N / 2; i++) {
        Minim = INF;
        start = 1;
        sfarsit = N / 2;

        Interog(1, 1, N / 2, impare);
        Minim1 = Minim;

        Minim = INF;
        start = app_on_pos[Minim1];
        sfarsit = N / 2;
        Interog(1, 1, N / 2, pare);
        Minim2 = Minim;

        cout << Minim1 << ' ' << Minim2 << ' ';

        poz = app_on_pos[Minim1]; val = INF;
        Update(1, 1, N / 2, impare);

        poz = app_on_pos[Minim2]; val = INF;
        Update(1, 1, N / 2, pare);
    }
    return 0;
}