#include <bits/stdc++.h>
using namespace std;
void search(int N, string S, int k) {
  string key = "abcdefghijkl";
  S += key[k];
  if (N == 0) {
    cout << S << endl;
    return;
  } else {
    for (int i = 0; i < 2; i++) {
      search(N - 1, S, k + i);
    }
    return;
  }
}
int main() {
  int N;
  cin >> N;
  search(N - 1, "", 0);
}
