n = int(input())
s = 'abcdefghijklmopqrstuvwxyz'

a = [0] * 18
x = 'a'
for i in range(n - 1):
    res = x
    for j in range(18):
        res += s[a[j]]
    x = res[-1]
    a[i // 25] += 1
    print(res)
print(x + 'n')