import math

al = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j"]

N = int(input())
if N == 1:
  print(al[0])
else:
  S = [[""] * math.factorial(i+1) for i in range(N-1)]
  S[0][0] = al[0]

  for i in range(1, N-1):
    prev_S = S[i-1]
    al_use = al[:i+1]
    S[i] = [s + a for s in prev_S for a in al_use]

  prev_S = S[N-2]
  al_use = al[:N]
  for s in prev_S:
    for a in al_use:
      print(s + a)
