#include <bits/stdc++.h>
using namespace std;
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << " " << to_string(H);
  debug_out(T...);
}
template <class T>
inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
using ll = long long;
using P = pair<ll, ll>;
constexpr long double PI = 3.14159265358979323846264338327950288L;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
class DStringEquivalence {
 public:
  int n;
  void dfs(vector<int>& v, int used) {
    if (v.size() == n) {
      for (auto e : v) {
        cout << (char)(e + 'a');
      }
      cout << '\n';
      return;
    }
    for (int i = 0; i <= used; i++) {
      v.push_back(i);
      dfs(v, i + 1);
      v.pop_back();
    }
  }
  void solve(istream& cin, ostream& cout) {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> n;
    vector<int> v;
    dfs(v, 0);
  }
};
signed main() {
  DStringEquivalence solver;
  std::istream& in(std::cin);
  std::ostream& out(std::cout);
  solver.solve(in, out);
  return 0;
}
