from operator import itemgetter
a = ("a", "b", "c", "d", "e")
N = int(input())
L = [0]*N

alpha=list('abcdefghijk')
print('a'*N)
for i in range(N,0,-1):
    for j in range(1,i,1):
        L[-j]+=1
        print(''.join([alpha[i] for i in L]))
