#include <bits/stdc++.h>
using namespace std;
int n;
void dfs(string s, char high) {
  if (s.size() == n)
    printf("%s\n", s.c_str());
  else
    for (char c = 'a'; c <= high; ++c) dfs(s + c, high > c ? high : high + 1);
}
int main() {
  scanf("%d", &n);
  dfs("", 'a');
  return 0;
}
