def base_10_to_n(x, n):
    out = [0] * 4
    for i in range(4):
        out[i] = x % n
        x //= n
    return out

n = int(input())
alphabet = "abcdefghijklmopqrstuvwxyz"
pre = alphabet[0]

for i in range(n-1):
    x = base_10_to_n(i, 25)
    last = alphabet[x[0]]
    print(pre + alphabet[x[3]] + alphabet[x[2]] + alphabet[x[1]] + last)
    pre = last
print(pre + "n")