n=int(input())
char=[chr(i) for i in range(97, 97+26)]

ans=["a"]
before=0

for i in range(2,n+1):
    for c in range(len(ans)):
        From=char.index(ans[c][-1])
        for m in range(From+2):
            ans.append(ans[c]+char[m])
    #print(ans)
    
for g in range(len(ans)):
    if len(ans[g])==n:
        print(ans[g])