n = int(input())-1
s = set()
x = "a"
L = "abcdefghijklmopqrstuvwxyz"
from random import choice
while n:
    y = x[-1]
    for i in range(19):
        if y not in s:
            print(y)
            n -= 1
            x = y
            s.add(y)
            break
        else:
            y += choice(L)
print(x[-1]+"n")