#include <bits/stdc++.h>
using namespace std;
template <class A>
void pr(A a) {
  cout << a;
  cout << '\n';
}
template <class A, class B>
void pr(A a, B b) {
  cout << a << ' ';
  pr(b);
}
template <class A, class B, class C>
void pr(A a, B b, C c) {
  cout << a << ' ';
  pr(b, c);
}
template <class A, class B, class C, class D>
void pr(A a, B b, C c, D d) {
  cout << a << ' ';
  pr(b, c, d);
}
template <class A>
void PR(A a, long long n) {
  for (long long i = (long long)(0); i < (long long)(n); i++) {
    if (i) cout << ' ';
    cout << a[i];
  }
  cout << '\n';
}
long long check(long long n, long long m, long long x, long long y) {
  return x >= 0 && x < n && y >= 0 && y < m;
}
const long long MAX = 1e9 + 7, MAXL = 1LL << 61, dx[4] = {-1, 0, 1, 0},
                dy[4] = {0, 1, 0, -1};
long long n;
vector<string> v;
void dfs(string s, int k) {
  bool ff = 1;
  for (long long i = (long long)(0); i < (long long)(s.size()); i++) {
    if (s[i] == '-') ff = 0;
  }
  if (ff || k >= n) {
    v.push_back(s);
    return;
  }
  for (long long t = (long long)(1); t < (long long)(1 << s.size()); t++) {
    bool f = 0;
    string r = s;
    for (long long i = (long long)(0); i < (long long)(s.size()); i++) {
      if (t & (1 << i)) {
        if (s[i] != '-') goto next;
        r[i] = (char)(k + 'a');
        f = 1;
      }
      if (r[i] == '-' && !f) goto next;
    }
    dfs(r, k + 1);
  next:;
  }
}
void Main() {
  cin >> n;
  dfs(string(n, '-'), 0);
  sort((v).begin(), (v).end());
  v.erase(unique((v).begin(), (v).end()), v.end());
  for (long long i = (long long)(0); i < (long long)(v.size()); i++) pr(v[i]);
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  Main();
  return 0;
}
