#include <bits/stdc++.h>
using namespace std;
string ans = "aaaaaaaaaa";
string str = "abcdefghij";
int N;
void find(int pos) {
  if (pos == N) {
    for (int i = 0; i < N; i++) cout << ans[i];
    cout << "\n";
    return;
  }
  for (int i = 0; i < pos + 1; i++) {
    if (pos != 0 && (str[i] - ans[pos - 1] > 1)) {
      return;
    } else {
      ans[pos] = str[i];
      find(pos + 1);
    }
  }
}
int main() {
  cin >> N;
  find(0);
}
