#include <iostream>
#include <string>
#include <vector>

using namespace std;

const string letter[] = { "a", "b", "c", "d", "e", "f", "g", "h", "i", "j",
                          "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u",
                          "v", "w", "x", "y", "z" };

void addeverywhere(string base, int N, vector<string> & set)
{ int sz = base.length();
  for (int i = 0; i <= sz; i += 1)
  { string ext = base.substr(0, i) + letter[sz] + base.substr(i);
    if (ext.length() == N)
      set.push_back(ext);
    else
      addeverywhere(ext, N, set); } }

int main(int argc, char * argv[])
{ int N = atol(argv[1]);
  vector<string> set;
  addeverywhere("", N, set);
  for (int i = 0; i < set.size(); i += 1)
    cout << i << ": " << set.at(i) << "\n"; }