#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 main() {
  cin.tie(0), ios::sync_with_stdio(false);
  int n;
  cin >> n;
  queue<string> q;
  q.push("a");
  while (!q.empty()) {
    string x = q.front();
    q.pop();
    if (n == x.size()) cout << x << endl;
    if (n < x.size()) continue;
    bool flag = false;
    for (char a = 'a'; a <= 'z'; a++) {
      q.push(x + a);
      if (flag) break;
      if (x.back() == a) flag = true;
    }
  }
  return 0;
}
