l = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n"]
n = int(input())
ans = [[] for i in range(n)]
ans[0].append("a")

for i in range(1,n):
    print(ans)
    for j in ans[i-1]:
        a = 0
        for k in j:
            a = max(a,ord(k)-ord("a"))
        for k in range(a+2):
            an = j + l[k]
            ans[i].append(an)
count = ans[-1]
count.sort()
for i in count:
    print(i)
