#include <bits/stdc++.h>
using namespace std;
using ll = long long;
template <class T, class U>
using P = pair<T, U>;
template <class T>
using Heap = priority_queue<T>;
template <class T>
using heaP = priority_queue<T, vector<T>, greater<T>>;
template <class T, class U>
using umap = unordered_map<T, U>;
template <class T>
using uset = unordered_set<T>;
template <class T>
bool ChangeMax(T& a, const T& b) {
  if (a >= b) return false;
  a = b;
  return true;
}
template <class T>
bool ChangeMin(T& a, const T& b) {
  if (a <= b) return false;
  a = b;
  return true;
}
template <class T, size_t N, class U>
void Fill(T (&a)[N], const U& v) {
  fill((U*)a, (U*)(a + N), v);
}
template <class T>
istream& operator>>(istream& is, vector<T>& v) {
  for (auto& e : v) is >> e;
  return is;
}
vector<string> ans;
void dfs(string s, int depth) {
  if (depth == 0) {
    ans.push_back(s);
    return;
  }
  for (int i = 'a'; i <= s.back() + 1; ++i) dfs(s + char(i), depth - 1);
}
int main() {
  int n;
  cin >> n;
  string s = "a";
  dfs(s, n - 1);
  sort(ans.begin(), ans.end());
  for (string& e : ans) cout << e << endl;
  return 0;
}
