#include <bits/stdc++.h>
using namespace std;
template <typename P, typename Q>
ostream& operator<<(ostream& os, pair<P, Q> p) {
  os << "(" << p.first << "," << p.second << ")";
  return os;
}
template <typename P, typename Q>
istream& operator>>(istream& is, pair<P, Q>& p) {
  is >> p.first >> p.second;
  return is;
}
template <typename T>
ostream& operator<<(ostream& os, vector<T> v) {
  os << "(";
  for (auto& i : v) os << i << ",";
  os << ")";
  return os;
}
template <typename T>
istream& operator>>(istream& is, vector<T>& v) {
  for (auto& i : v) is >> i;
  return is;
}
template <typename T>
ostream& operator<<(ostream& os, set<T> s) {
  os << "#{";
  for (auto& i : s) os << i << ",";
  os << "}";
  return os;
}
template <typename K, typename V>
ostream& operator<<(ostream& os, map<K, V> m) {
  os << "{";
  for (auto& i : m) os << i << ",";
  os << "}";
  return os;
}
template <typename T>
inline T setmax(T& a, T b) {
  return a = std::max(a, b);
}
template <typename T>
inline T setmin(T& a, T b) {
  return a = std::min(a, b);
}
using lli = long long int;
using ull = unsigned long long;
using point = complex<double>;
using str = string;
template <typename T>
using vec = vector<T>;
int di[] = {0, 1, -1, 0, 1, -1, 1, -1};
int dj[] = {1, 0, 0, -1, 1, -1, -1, 1};
constexpr lli mod = 1e9 + 7;
char buff[11];
int n;
void bt(int m, char c) {
  if (n == m) {
    buff[m] = '\0';
    puts(buff);
    return;
  }
  for (char d = 'a'; d < c; ++d) {
    buff[m] = d;
    bt(m + 1, c);
  }
  buff[m] = c + 1;
  bt(m + 1, c + 1);
  return;
}
int main(int argc, char* argv[]) {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  while (cin >> n) {
    bt(0, 'a' - 1);
  }
  return 0;
}
