#include <bits/stdc++.h>
using namespace std;
template <class T>
bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
const long long INF = 1LL << 60;
const int inf = (1 << 30) - 1;
const int mod = 1e9 + 7;
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  int n;
  cin >> n;
  vector<string> a;
  queue<string> que;
  que.push("a");
  while (!que.empty()) {
    string t = que.front();
    que.pop();
    int k = t.size();
    if (k == n) {
      a.push_back(t);
      continue;
    }
    for (int i = 0; i <= t[t.size() - 1] - 'a' + 1; i++) {
      que.push(t + char(i + 'a'));
    }
  }
  sort(a.begin(), a.end());
  for (string x : a) {
    cout << x << endl;
  }
}
