program eeer;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
   n, i, j, e: integer;
   a: array[0..30, 0..30] of integer;
   w: boolean;
   s: string;

begin
   reset(input, 'string.in');
   rewrite(output, 'string.out');
   readln(n);
   e := 1;
   w := true;
   s := 'a';
   for i := 1 to (n * n) do
   begin
      if (w = false) then
      begin
         for j := 0 to (n-1) do
         begin
            if (a[e, ((j - e + n) mod n + 1)] = 0) then
            begin
               a[e, ((j - e + n) mod n + 1)] := 1;
               e := ((j - e + n) mod n + 1);
               break;
            end;
         end;
      end
      else
      begin
         for j := 0 to (n-1) do
         begin
            if (a[e, ((e - j + n - 1) mod n + 1)] = 0) then
            begin
               a[e, ((e - j + n - 1) mod n + 1)] := 1;
               e := ((e - j + n - 1) mod n + 1);
               break;
            end;
         end;
      end;

      s := s + chr (e + 96);
      if (e = 1) then
         w := false;
      if (e = n) then
         w := true;
   end;
   writeln(s);
   //readln; readln;
end.