#include <bits/stdc++.h>
using namespace std;
const int INF = 1001001001;
const int MOD = 1e9 + 7;
const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, 1, 0, -1};
template <class T>
inline bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
inline bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
int main() {
  cin.tie(0), ios::sync_with_stdio(false);
  int n;
  cin >> n;
  vector<string> ans;
  for (int bit = 0; bit < int((1 << n) / 2); bit++) {
    string res = "";
    for (int i = 0; i < int(n); i++) {
      if (bit >> i & 1)
        res = "b" + res;
      else
        res = "a" + res;
    }
    ans.push_back(res);
  }
  sort((ans).begin(), (ans).end());
  for (int i = 0; i < int(ans.size()); i++) cout << ans[i] << endl;
  return 0;
}
