// Slower C++ solution:
/**

 *    author  : 𝒌𝒚𝒐𝒎𝒖𝒌𝒚𝒐𝒎𝒖𝒑𝒖𝒓𝒊𝒏

 *    created : 2020-03-14 22:54:55

**/



#include <iostream>

#include <deque>

#include <map>

#include <queue>

#include <set>

#include <stack>

#include <string>

#include <vector>

#include <algorithm>

#include <cmath>

#include <complex>

#include <numeric>

#include <bitset>

#include <cassert>

#include <cctype>

#include <iomanip>

#include <random>

#include <utility>

#include <chrono>



using namespace std;



using int64 = long long;



template<class T> using binary_heap = std::priority_queue<T, std::vector<T>, std::greater<T>>;

template<class T> std::ostream& operator<<(std::ostream& os, const std::vector<T>& vec) { os << '{'; size_t n = vec.size(); for (size_t i = 0; i < n; ++i) { os << vec[i]; if (i != n - 1) os << ','; } os << '}'; return os; }

template<class T, class U> std::ostream& operator<<(std::ostream& os, const std::pair<T, U>& p) { return os << '{' << p.first << " " << p.second << '}'; }

template<class T, class U> std::ostream& operator<<(std::ostream& os, const std::map<T, U>& mp) { os << '{'; for (auto it = mp.begin(); it != mp.end(); ++it) { os << '{' << it->first << ':' << it->second << '}'; if (it != --mp.end()) os << ','; } os << '}'; return os; }

template<class T> std::ostream& operator<<(std::ostream& os, const std::set<T>& st) { os << '{'; for (auto it = st.begin(); it != st.end(); ++it) { os << *it; if (it != --st.end()) os << ','; } os << '}'; return os; }

template<class T> std::istream& operator>>(std::istream& is, std::vector<T>& vec) { size_t n = vec.size(); for (size_t i = 0; i < n; ++i) is >> vec[i]; return is; }



#define all(_) begin(_), end(_)

#define rall(_) rbegin(_), rend(_)



#ifdef LOCAL

#define debug(...) cerr << "[" << #__VA_ARGS__ << "]: ", debug_out(__VA_ARGS__)

#else

#define debug(...) 1728

#endif



void debug_out() { std::cerr << '\n'; }



template <class Head, class... Tail>

void debug_out(Head&& head, Tail&&... tail) {

  std::cerr << head;

  if (sizeof...(Tail) != 0) std::cerr << ", ";

  debug_out(std::forward<Tail>(tail)...);

}



int main() {

  ios_base::sync_with_stdio(false);

  cin.tie(nullptr);



  int n; cin >> n;



  vector<string> ans;



  auto DFS = [&](const auto& DFS, string s, char cur) -> void {

    if ((int) s.size() == n) {

      ans.emplace_back(s);

    } else {

      for (char c = 'a'; c <= cur; ++c) {

        if (c != cur) {

          DFS(DFS, s + c, cur);

        } else {

          DFS(DFS, s + c, (char)(cur + 1));

        }

      }

    }

  };



  DFS(DFS, "", 'a');



  sort(all(ans));

  for (auto x : ans) {

    cout << x << '\n';

  }



  return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.1901116576590214x):
/**

 *    author  : 𝒌𝒚𝒐𝒎𝒖𝒌𝒚𝒐𝒎𝒖𝒑𝒖𝒓𝒊𝒏

 *    created : 2020-03-15 01:37:45

**/



#include <iostream>

#include <deque>

#include <map>

#include <queue>

#include <set>

#include <stack>

#include <string>

#include <vector>

#include <algorithm>

#include <cmath>

#include <complex>

#include <numeric>

#include <bitset>

#include <cassert>

#include <cctype>

#include <iomanip>

#include <random>

#include <utility>

#include <chrono>



using namespace std;



using int64 = long long;



template<class T> using binary_heap = std::priority_queue<T, std::vector<T>, std::greater<T>>;

template<class T> std::ostream& operator<<(std::ostream& os, const std::vector<T>& vec) { os << '{'; size_t n = vec.size(); for (size_t i = 0; i < n; ++i) { os << vec[i]; if (i != n - 1) os << ','; } os << '}'; return os; }

template<class T, class U> std::ostream& operator<<(std::ostream& os, const std::pair<T, U>& p) { return os << '{' << p.first << " " << p.second << '}'; }

template<class T, class U> std::ostream& operator<<(std::ostream& os, const std::map<T, U>& mp) { os << '{'; for (auto it = mp.begin(); it != mp.end(); ++it) { os << '{' << it->first << ':' << it->second << '}'; if (it != --mp.end()) os << ','; } os << '}'; return os; }

template<class T> std::ostream& operator<<(std::ostream& os, const std::set<T>& st) { os << '{'; for (auto it = st.begin(); it != st.end(); ++it) { os << *it; if (it != --st.end()) os << ','; } os << '}'; return os; }

template<class T> std::istream& operator>>(std::istream& is, std::vector<T>& vec) { size_t n = vec.size(); for (size_t i = 0; i < n; ++i) is >> vec[i]; return is; }



#define all(_) begin(_), end(_)

#define rall(_) rbegin(_), rend(_)



#ifdef LOCAL

#define debug(...) cerr << "[" << #__VA_ARGS__ << "]: ", debug_out(__VA_ARGS__)

#else

#define debug(...) 1728

#endif



void debug_out() { std::cerr << '\n'; }



template <class Head, class... Tail>

void debug_out(Head&& head, Tail&&... tail) {

  std::cerr << head;

  if (sizeof...(Tail) != 0) std::cerr << ", ";

  debug_out(std::forward<Tail>(tail)...);

}



int main() {

  ios_base::sync_with_stdio(false);

  cin.tie(nullptr);



  int n; cin >> n;



  auto DFS = [&](const auto& DFS, string s, int cur) -> void {

    if ((int) s.size() == n) {

      cout << s << '\n';

    } else {

      for (char c = 'a'; c <= (char)('a' + cur); ++c) {

        if (c == (char)('a' + cur)) {

          DFS(DFS, s + c, cur + 1);

        } else {

          DFS(DFS, s + c, cur);

        }

      }

    }

  };



  string s = "";



  DFS(DFS, s, 0);



  return 0;

}