#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  int n;
  cin >> n;
  string s;
  vector<string> rs;
  for (int i = 0; i < n; ++i) {
    s = s + 'a';
  }
  cout << s << "\n";
  for (char ch = 'b'; ch <= 'z'; ++ch) {
    for (int i = n - 1; i >= (int)(ch - 'a'); --i) {
      s[i] = ch;
      cout << s << "\n";
    }
  }
  return 0;
}
