#include <bits/stdc++.h>
using namespace std;
int n;
void dfs(string s, char c) {
  if (s.length() == n) {
    cout << s << endl;
    return;
  }
  for (char chr = 'a'; chr <= c + 1; ++chr) {
    dfs(s + chr, chr);
  }
}
int main() {
  cin >> n;
  dfs("a", 'a');
  return 0;
}
