def sol(k):

    def gen(d, cur, s):
        if d == k:
            yield s
            return
        for i in range(0, cur+1):
            yield from gen(d+1, i+1, s+chr(97+i))

    return gen(0, 0, '')

def main():
    k = int(input())
    for x in sol(k):
        print(x)

if __name__ == '__main__':
    main()


