#include <bits/stdc++.h>
using namespace std;
char str[11];
int n;
void dfs(int idx, char c) {
  str[idx] = c;
  if (idx == n - 1) {
    cout << str;
    return;
  }
  dfs(idx + 1, c);
  dfs(idx + 1, c + 1);
}
int main() {
  cin >> n;
  str[n] = '\n';
  dfs(0, 'a');
  return 0;
}
