N = int(input())
alp = ["b","c","d","e","f","g","h","i","j","a"]
a = "a"
A = "a"
for i in range(N):
    word = [a]
    a = a + "a"
for i in range(N):
    word = [A]
    A = A + alp.pop(0)
word.pop(0)
word.sort()
s = "\n".join(word)
print(s)