def mi():return map(str,input().split())

n=int(input())
ans=["Sorry"]
if n==1:ans=["a"]
if n==2:ans=["aa","ab"]
if n==3:ans=["aaa","aab","aba","abb","abc"]
if n==4:ans=['aaaa', 'aaab','aaba', 'aabb', 'aabc','abaa', 'abab', 'abac','abba', 'abbb', 'abbc','abca', 'abcb', 'abcc', 'abcd']

for i in ans:
  print(i)