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