#include <bits/stdc++.h>
using namespace std;
const long long md = 1e9 + 7;
const long long MX = 2e5 + 5;
const long long INF = 1e18;
const long double PI = 4 * atan((long double)1);
long long power(long long a, long long n) {
  long long res = 1;
  while (n) {
    if (n % 2) res *= a;
    a *= a;
    n /= 2;
  }
  return res;
}
long long abst(long long a) { return ((a < 0) ? (-1 * a) : (a)); }
long long n;
vector<string> res;
void fun(string s) {
  if (s.size() == n) {
    res.push_back(s);
    return;
  }
  char chp;
  if (s.size() == 0)
    chp = 'a';
  else
    chp = s[s.size() - 1];
  if (s.size() != 0) chp++;
  for (char ch = 'a'; ch <= chp; ch++) {
    string q = s;
    q += ch;
    fun(q);
  }
  return;
}
int32_t main() {
  ios_base::sync_with_stdio(false), cin.tie(NULL);
  cin >> n;
  string s = "";
  fun(s);
  sort(res.begin(), res.end());
  for (long long i = 0; i < res.size(); i++) cout << res[i] << "\n";
  return 0;
}
