#include <bits/stdc++.h>
using namespace std;
const int inf = 1e9 + 7;
const long long INF = 1e18;
const int mod = 1000000007;
template <typename T1, typename T2>
inline bool chmin(T1& a, T2 b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
template <typename T1, typename T2>
inline bool chmax(T1& a, T2 b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <typename T>
T gcd(T a, T b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
template <typename T>
T lcm(T a, T b) {
  return a / gcd(a, b) * b;
}
template <typename T>
T pow(T a, int b) {
  return b ? pow(a * a, b / 2) * (b % 2 ? a : 1) : 1;
}
long long modpow(long long a, long long b, long long _mod) {
  return b ? modpow(a * a % _mod, b / 2, _mod) * (b % 2 ? a : 1) % _mod : 1;
}
template <class T>
ostream& operator<<(ostream& os, const vector<T>& vec) {
  for (auto& vi : vec) os << vi << " ";
  return os;
}
template <class T, class U>
ostream& operator<<(ostream& os, const pair<T, U>& p) {
  os << p.first << " " << p.second;
  return os;
}
template <typename T>
inline istream& operator>>(istream& is, vector<T>& v) {
  for (int j = 0; j < ((int)v.size()); ++j) is >> v[j];
  return is;
}
template <class T>
inline void add(T& a, int b) {
  a += b;
  if (a >= mod) a -= mod;
}
void solve();
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cout << fixed << setprecision(10);
  int T;
  T = 1;
  while (T--) {
    solve();
  }
}
int n;
int cnt = 0;
set<string> st;
void dfs(int d, vector<int> x) {
  if (d + 1 == n) {
    cnt++;
    string s;
    for (int i = 0; i < ((int)x.size()); ++i) s += 'a' + x[i];
    st.insert(s);
    return;
  }
  for (int i = 0; i < ((int)x.size()); ++i) {
    x.emplace_back(x[i]);
    dfs(d + 1, x);
    x.pop_back();
  }
  x.emplace_back(x.back() + 1);
  dfs(d + 1, x);
}
void solve() {
  cin >> n;
  vector<int> x;
  x.emplace_back(0);
  dfs(0, x);
  for (auto e : st) cout << e << endl;
}
