#include <bits/stdc++.h>
const int MGN = 10;
const int ARY_SZ_MAX = (int)1e7;
using namespace std;
using ll = long long;
using ull = unsigned long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vc = vector<char>;
using vvc = vector<vc>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vd = vector<double>;
using vs = vector<string>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using psl = pair<string, ll>;
string S = "abcdefghij";
string T;
int N;
void dfs(int n, string res) {
  if (n >= N - 1) {
    printf("%s\n", res.c_str());
    return;
  }
  for (auto c : T) {
    if (c > res.back() + 1) continue;
    dfs(n + 1, res + c);
  }
}
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cin >> N;
  T = S.substr(0, N);
  dfs(0, "a");
  return 0;
}
