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

int main() {
  int N;
  cin >> N;
  vector P(N, 0);
  for (int &i : P) cin >> i, --i;
  vector idx(N, 0), pr(N, -1), ne(N, -1);
  for (int i = 0; i < N; i++) {
    idx[P[i]] = i;
  }
  for (int i = 0; i < N - 1; i++) {
    ne[P[i]] = P[i + 1];
  }
  for (int i = 1; i < N; i++) {
    pr[P[i]] = P[i - 1];
  }
  vector ans(0, 0), ok(N, 1);
  for (int i = 0; i < N; i++) {
    if (ok[i] && ne[i] != -1) {
      int x = i, y = ne[i];
      ans.push_back(x);
      ans.push_back(y);
      ok[x] = 0, ok[y] = 0;
      if (ne[y] != -1) pr[ne[y]] = pr[x];
      if (pr[x] != -1) ne[pr[x]] = ne[y];
    }
  }
  for (int i = 0; i < N; i++) {
    if (i) cout << ' ';
    cout << ans[i] + 1;
  }
  cout << '\n';
}