N=int(input())
queue={"a":[],"b":[]}
for bit in range(1,1<<N):
    S=""
    for i in range(N):
        if bit&1<<i:
            S+="a"
        else:
            S+="b"
    queue[S[0]].append(S)
ans="a"
for n in range(N):
    if n==N-1:
        ans=ans[:-1]+"n"
        break
    print(ans)
    ans=queue[ans[-1]].pop()