N=int(input())

ans='a'*N
ans_code=[0]*N
for i in range(N):
    ans_code[i]=ord(ans[i])
#print(ans_code)

for k in ans_code:
        print(chr(k),end='')
print('')

for i in range(1,N):
    for j in range(1,i+1):
        ans_code[-j]+=1
    #print(ans_code)
    for k in ans_code:
        print(chr(k),end='')
    print('')
    

"""
ans[-1]
for i in range(N):
    ans[]
"""