#include <bits/stdc++.h>
using namespace std;
signed main() {
  int n;
  cin >> n;
  char str[10];
  for (int i = 0; i < 10; i++) {
    if (i < n) {
      str[i] = 'a';
    } else {
      str[i] = '\0';
      break;
    }
  }
  cout << str << endl;
  for (int i = 0; i < n - 1; i++) {
    int j = n - 1;
    int targ = i;
    while (j > targ) {
      str[j]++;
      cout << str << endl;
      j--;
    }
  }
}
