n = int(input())
alphabet = "abcdefghijklmnopqrstuvwxyz"
pre = alphabet[0]
for i in range(n-1):
    last = alphabet[i%26]
    print(pre + alphabet[i//(26**3)] + alphabet[i//(26**2)] + alphabet[i//(26**1)] + last)
    pre = last
print(pre + "n")