n = int(input())
l = [0]*20
oa = ord('a')
for i in range(n-1):
    s = ''.join(map(lambda x:chr(oa+x), l))
    print(s)
    l[18] += 1
    if l[18] > 25:
        idx = 18
        while l[idx] > 25:
            l[idx] = 0
            l[idx-1] += 1
            idx -= 1
print('an')