#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int a[10];
int mx[10];
void prt(int n) {
  static const char* t = "abcdefghijklmnopqrstuvwxyz";
  for (int i = 0; i < n; i++) {
    cout << t[a[i]];
  }
  cout << endl;
}
int nx(int n) {
  int rc = 0;
  int i = n - 1;
  while (i >= 0) {
    a[i]++;
    int c_mx = 0;
    if (i > 0) {
      if (a[i] <= mx[i - 1] + 1) {
        mx[i] = a[i];
        return 0;
      }
      a[i] = 0;
    }
    i--;
  }
  return 1;
}
int main() {
  int n;
  for (n = 0; n < 10; n++) {
    a[n] = mx[n] = 0;
  }
  cin >> n;
  while (1) {
    prt(n);
    if (nx(n)) {
      break;
    }
  }
  return 0;
}
