#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vl = vector<ll>;
using vvl = vector<vector<ll>>;
using pl = pair<ll, ll>;
using vpl = vector<pl>;
using vvpl = vector<vpl>;
const ll MOD = 1000000007;
const ll MOD9 = 998244353;
const int inf = 1e9 + 10;
const ll INF = 4e18;
const ll dy[8] = {1, 0, -1, 0, 1, 1, -1, -1};
const ll dx[8] = {0, -1, 0, 1, 1, -1, 1, -1};
template <class T>
inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
vector<string> ans;
ll n;
void dfs(string& a) {
  if (a.size() == n) {
    ans.push_back(a);
    return;
  }
  char x = *a.rbegin();
  for (ll i = 0; i < x - 'a' + 2; i++) {
    char y = 'a' + i;
    string k = a + y;
    dfs(k);
  }
}
int main() {
  cin >> n;
  string k = "a";
  dfs(k);
  sort((ans).begin(), (ans).end());
  for (auto p : ans) cout << p << endl;
}
