n = int(input())
alp = list('abcdefghijklmnopqrstuvwxyz')
ll = []
for i in range(26):
    for j in range(26):
        for k in range(26):
            for l in range(26):
                ll.append('a'+alp[i]+alp[j]+alp[k]+alp[l]+'a')

for i in range(n-1):
    print(ll[i])
print(ll[n-1][:-1]+'n')