from string import ascii_lowercase
from functools import lru_cache
n = int(input())

@lru_cache
def make(n):
    if n == 1:
        return ['a']
    else:
        lst = []
        for s in make(n-1):
            for c in ascii_lowercase[:len(set(s))+1]:
                lst.append(s + c)
        return lst
for s in make(n):
    print(*s, sep='')