#include <bits/stdc++.h>
using ll = long long;
constexpr ll mod = 1e9 + 7;
constexpr ll INF = 1LL << 60;
ll gcd(ll n, ll m) {
  ll tmp;
  while (m != 0) {
    tmp = n % m;
    n = m;
    m = tmp;
  }
  return n;
}
ll lcm(ll n, ll m) { return abs(n) / gcd(n, m) * abs(m); }
template <class T>
inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
using namespace std;
int n;
vector<string> ans;
void dfs(int id, string s) {
  if (id == n) {
    ans.push_back(s);
    return;
  }
  for (int i = (int)0; i < (int)id + 1; ++i) {
    if ((id == 0) || abs((s.back() - 'a') - i) <= 1)
      dfs(id + 1, s + string{char('a' + i)});
  }
}
void solve() {
  cin >> n;
  dfs(0, "");
  sort(ans.begin(), ans.end());
  for (int i = (int)0; i < (int)ans.size(); ++i) cout << ans[i] << endl;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout << fixed << setprecision(15);
  solve();
  return 0;
}
