#include <bits/stdc++.h>
using namespace std;
template <typename T0, typename T1>
std::ostream& operator<<(std::ostream& os, const map<T0, T1>& v) {
  for (typename map<T0, T1>::const_iterator p = v.begin(); p != v.end(); p++) {
    os << p->first << ": " << p->second << " ";
  }
  return os;
}
template <typename T0, typename T1>
std::ostream& operator<<(std::ostream& os, const pair<T0, T1>& v) {
  os << v.first << ": " << v.second << " ";
  return os;
}
template <typename T>
std::ostream& operator<<(std::ostream& os, const vector<T>& v) {
  for (int i = 0; i < (int)v.size(); i++) {
    os << v[i] << " ";
  }
  return os;
}
template <typename T>
std::ostream& operator<<(std::ostream& os, const set<T>& v) {
  vector<T> tmp(v.begin(), v.end());
  os << tmp;
  return os;
}
template <typename T>
std::ostream& operator<<(std::ostream& os, const deque<T>& v) {
  vector<T> tmp(v.begin(), v.end());
  os << tmp;
  return os;
}
template <typename T>
std::ostream& operator<<(std::ostream& os, const vector<vector<T>>& v) {
  for (int i = 0; i < (int)v.size(); i++) {
    os << v[i] << endl;
  }
  return os;
}
template <typename T>
void maxUpdate(T& a, T b) {
  a = max(a, b);
}
template <typename T>
void minUpdate(T& a, T b) {
  a = min(a, b);
}
string s;
vector<string> ss;
void f(int i, int k, int N) {
  if (i == N) {
    ss.push_back(s);
    return;
  }
  for (long long j = 0, _n = (k + 1); (j) < (long long)_n; ++j) {
    s[i] = 'a' + j;
    f(i + 1, j + 1, N);
  }
}
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  long long N;
  while (cin >> N) {
    s = string(N, ' ');
    ss.clear();
    f(0, 0, N);
    for (long long i = 0, _n = (ss.size()); (i) < (long long)_n; ++i) {
      cout << ss[i] << endl;
    }
  }
  return 0;
}
