#include <bits/stdc++.h>
const int MOD = 1e9 + 7;
const int iINF = 2147483647 / 2;
const long long int llINF = 9223372036854775807 / 2;
using namespace std;
using ll = long long int;
using vl = vector<ll>;
using vvl = vector<vector<ll>>;
using vvvl = vector<vector<vector<ll>>>;
bool paircomp(const pair<ll, ll> &a, const pair<ll, ll> &b) {
  if (a.first == b.first) return a.second < b.second;
  return a.first < b.first;
}
ll POW(ll n, ll m) {
  if (m == 0) {
    return 1;
  } else if (m % 2 == 0) {
    ll tmp = POW(n, m / 2);
    return (tmp * tmp);
  } else {
    return (n * POW(n, m - 1));
  }
}
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ll N;
  cin >> N;
  vector<string> A;
  A.push_back("a");
  map<string, bool> M;
  for (ll i = (1); i < (N); i++) {
    vector<string> B;
    for (auto &a : A) {
      for (ll k = 0; k < (i); k++) {
        string s = a.substr(0, k + 1) + a.substr(k, 1);
        if (k != i - 1) s += a.substr(k + 1);
        if (M.find(s) == M.end()) {
          B.push_back(s);
          M[s] = true;
        }
      }
    }
    string s;
    for (ll j = 0; j < (i + 1); j++) s += ('a' + j);
    B.push_back(s);
    A = B;
  }
  sort((A).begin(), (A).end());
  for (auto &a : A) cout << a << endl;
  return 0;
}
