n = int(input())
al = [chr(i) for i in range(97,97+26)]

dpn = ['a']
dpp = []
if n == 1:
    print('a')
    exit()
for i in range(1,n):
    for j in dpn:
        for k in al[:ord(j[-1])-97+2]:
            if i != n-1:
                dpp.append(j + k)
            else:
                print(j+k)
    if i != n-1:
        dpn = dpp
        dpp = []
