CR

#include <iostream>
#include <cmath>
#include <vector>

using std::string;
using std::cin;
using std::cout;
using std::vector;

void print(vector<int> &v, int k) {
  int n = v.size();
  for (int i = 0; i < n; i += k) {
    cout << v[i] << ' ';
  } --n;
  for (int i = n - n%k; i >= 0; i -= k) {
    v.erase(v.begin() + i);
  }
  cout << '\n';
  cout.flush();
}

int main() {
  int n; cin >> n;
  vector<int> v(n);
  for (int & el : v) cin >> el;
  print(v, 2);
  print(v, 2);
  print(v, 1);
}