#include <bits/stdc++.h>
using namespace std;
const int INF = 1001001001;
const int MOD = 1e9 + 7;
const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, 1, 0, -1};
template <class T>
inline bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
inline bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
int n;
void dfs(string ans, char mx) {
  if (ans.size() == n) {
    cout << ans << endl;
    return;
  }
  for (char c = 'a'; c <= mx + 1; c++) {
    dfs(ans + c, max(mx, c));
  }
}
int main() {
  cin.tie(0), ios::sync_with_stdio(false);
  cin >> n;
  dfs("", 'a');
  return 0;
}
