n = int(input())
s = 'abcdefghijklmopqrstuvwxyz'


def base10to(n, b=25):
    if int(n / b):
        return base10to(int(n / b), b) + ' ' + str(n % b)
    else:
        return str(n % b)


x = 'a'
for i in range(n - 1):
    res = x
    for j in base10to(i).split():
        res += s[int(j)]
    x = res[-1]
    print(res)
print(x + 'n')