#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int mod = 998244353;
struct mint {
  ll x;
  mint(ll x = 0) : x((x % mod + mod) % mod) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += mod - a.x) >= mod) x -= mod;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const { return mint(*this) += a; }
  mint operator-(const mint a) const { return mint(*this) -= a; }
  mint operator*(const mint a) const { return mint(*this) *= a; }
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1) a *= *this;
    return a;
  }
  mint inv() const { return pow(mod - 2); }
  mint &operator/=(const mint a) { return *this *= a.inv(); }
  mint operator/(const mint a) const { return mint(*this) /= a; }
};
istream &operator>>(istream &is, const mint &a) { return is >> a.x; }
ostream &operator<<(ostream &os, const mint &a) { return os << a.x; }
int n;
void dfs(string s, int x, vector<string> &A) {
  if (s.size() == n) {
    A.emplace_back(s);
    return;
  }
  for (int i = 0; i <= x + 1; ++i) {
    char c = ('a' + i);
    dfs(s + c, i, A);
  }
}
int main() {
  cin >> n;
  vector<string> A;
  dfs("a", 0, A);
  for (int i = 0; i < A.size(); ++i) {
    cout << A[i] << endl;
  }
  return 0;
}
