N = int(input())
a_ch = [chr(ch) for ch in range(ord('a'), ord('j'))]

def DFS(s, mx):
  if len(s) == N:
    print(s)
  else:
    for i in range(mx + 1):
      if i == mx:
        DFS(s + a_ch[i], mx + 1)
      else:
        DFS(s + a_ch[i], mx)

DFS('', 0)