N = gets.to_i

def build_str(ch, len)
  res = ''

  (len - 1).times do
    res << ch
    res << ch.succ
  end
  res << ch

  ch.succ!

  if ch == 'z'
    ch = 'a'
  else
    ch.succ!
  end

  res
end

cur = 'a'
ans = ''
n = N

while n > 0
  len = 0
  cnt = 0

  while (cnt * (cnt + 1)) / 2 + (cnt * (cnt - 1)) / 2 <= n
    cnt += 1
    len += 1
  end
  cnt -= 1
  len -= 1

  n -= (cnt * (cnt + 1)) / 2 + (cnt * (cnt - 1)) / 2
  str = build_str(cur, len)
  ans << str
end

puts ans