#include <bits/stdc++.h>
using namespace std;
using LL = long long;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<LL>;
using VVL = vector<VL>;
using VD = vector<double>;
using VVD = vector<VD>;
using PII = pair<int, int>;
using PDD = pair<double, double>;
using PLL = pair<LL, LL>;
using VPII = vector<PII>;
template <typename T>
using VT = vector<T>;
template <typename T>
inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <typename T>
inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
const int INF = 1e9;
const int MOD = INF + 7;
const LL LLINF = 1e18;
int main(void) {
  int N;
  cin >> N;
  set<string> se;
  for (int(i) = 0; (i) < ((1 << N)); (i)++) {
    char nxt = 'b';
    string S = string(N, 'a');
    for (int(j) = (1); (j) < (N); (j)++)
      if (i & (1 << j)) {
        S[j] = nxt++;
      }
    se.emplace(S);
  }
  for (auto &&e : (se)) {
    cout << e << endl;
  }
}
