n = gets.to_s.to_i
op = [] of Int32
while n > 1
  if n.odd?
    n -= 1
    op << 1
  end
  n //= 2
  op << 2
end

cnt = [0]
op.reverse.each do |o|
  case o
  when 1
    x = cnt[0] + 1
    cnt = [x] + cnt + [x]
  when 2
    x = cnt[0]
    cnt = [x] + cnt + [x]
  end
end

ans = cnt.map(&.%(26).+('a'.ord).chr).join
puts ans