#include <bits/stdc++.h>
using namespace std;
using ll = long long;
template <class T>
bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
inline void Yes(bool condition) {
  if (condition)
    cout << "Yes"
         << "\n";
  else
    cout << "No"
         << "\n";
}
template <class itr>
void cins(itr first, itr last) {
  for (auto i = first; i != last; i++) {
    cin >> (*i);
  }
}
template <class itr>
void array_output(itr start, itr goal) {
  string ans = "", k = " ";
  for (auto i = start; i != goal; i++) ans += to_string(*i) + k;
  if (!ans.empty()) ans.pop_back();
  cout << ans << "\n";
}
ll gcd(ll a, ll b) { return a ? gcd(b % a, a) : b; }
const ll INF = 1e15;
const ll MOD = 1000000007;
const ll MOD2 = 998244353;
const ll MAX = 2010;
constexpr ll nx[8] = {1, 0, -1, 0, -1, -1, 1, 1};
constexpr ll ny[8] = {0, 1, 0, -1, -1, 1, -1, 1};
string s = "";
vector<string> ans;
void make(int cnt, bool flag) {
  if (cnt == 0) {
    ans.push_back(s);
  } else {
    if (!flag) {
      s += (s[s.length() - 1] + 1);
      make(cnt - 1, 0);
      s.pop_back();
    }
    s += 'a';
    make(cnt - 1, 0);
    s.pop_back();
  }
}
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  int n;
  cin >> n;
  make(n, 1);
  sort((ans).begin(), (ans).end());
  for (ll i = ll(0); i < ll(ans.size()); ++i) {
    cout << ans[i] << "\n";
  }
}
