#include <bits/stdc++.h>
using namespace std;
int flood[1000001][2], that[1001];
bool used[1001];
int main() {
  int n;
  cin >> n;
  n *= 2;
  for (int i = 1; i <= n; i++)
    for (int j = 1; j < i; j++) {
      int x;
      cin >> x;
      flood[x][0] = i;
      flood[x][1] = j;
    }
  used[0] = 1;
  for (int i = 1000000; i > 0; i--) {
    if (!used[flood[i][0]] && !used[flood[i][1]]) {
      used[flood[i][0]] = 1;
      used[flood[i][1]] = 1;
      that[flood[i][0]] = flood[i][1];
      that[flood[i][1]] = flood[i][0];
    }
  }
  for (int i = 1; i <= n; i++) {
    if (i > 1) cout << ' ';
    cout << that[i];
  }
}
