#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr ll atcoder_mod = 1e9 + 7;
template <typename T = int>
T in() {
  T x;
  cin >> x;
  return (x);
}
template <typename T = int, typename C = vector<T>>
C vecin(int N) {
  C x(N);
  for (int i = 0; i < (N); ++i) {
    x[i] = in<T>();
  }
  return move(x);
}
void vout() { cout << endl; }
template <typename Head, typename... Tail>
void vout(Head&& h, Tail&&... t) {
  cout << ' ' << h;
  vout(forward<Tail>(t)...);
}
void out() { cout << endl; }
template <typename Head, typename... Tail>
void out(Head&& h, Tail&&... t) {
  cout << h;
  vout(forward<Tail>(t)...);
}
void dfs(int depth, string str, int N) {
  if (depth == N) {
    out(str);
    return;
  }
  char ch = str.back();
  for (int i = 0; i <= (ch - 'a') + 1; i++) {
    dfs(depth + 1, str + (char)('a' + i), N);
  }
}
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(10);
  int N = in();
  dfs(1, "a", N);
  return 0;
}
