# frozen_string_literal: true

def solve
  return 'a' if N == 1

  centers_of_word = ('a'..'z').to_a.repeated_permutation(18).take(N).map(&:join)
  centers_of_word[0..(N - 2)].map { %(a#{_1}a) }.push(%(a#{centers_of_word[-1]}n))
end

N = gets.to_i

puts solve