import sys
sys.setrecursionlimit(1000000)

N = int(input())
alpha = [chr(ord('a') + i) for i in range(26)]

def dfs(s, max_i):
  if len(s) == N:
    print(s)
  else:
    for i in range(97,max_i+1):
      dfs(s+chr(i), i if i != max_i else max_i+1)

dfs('', 97)