#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = long long unsigned;
using P = pair<int, int>;
const int INF = 1001001;
int main() {
  int n;
  cin >> n;
  string ans = string(n, 'a');
  vector<char> p(n, 'a');
  for (int k = 0; k < (n); ++k) {
    cout << p[k];
  }
  cout << endl;
  for (int i = 0; i < (n); ++i) {
    for (int j = n - 1; j > i; j--) {
      p[j]++;
      for (int k = 0; k < (n); ++k) {
        cout << p[k];
      }
      cout << endl;
    }
  }
}
