#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;
int n;
void dfs(string s, char mx) {
  if (s.size() == n) {
    cout << s << endl;
    return;
  }
  for (char c = 'a'; c <= mx; c++) {
    string t = s;
    t += c;
    dfs(t, c + 1);
  }
}
int main() {
  cin >> n;
  dfs("a", 'a' + 1);
  return 0;
}
