def square(n : Int32)
  sqrt = Math.sqrt(n).to_i + 1
  while sqrt * sqrt > n
    sqrt -= 1
  end
  sqrt
end

n = read_line.to_i
a = [] of Int32
while n > 0
  s = square(n)
  a << s - 1
  n -= s * s
end

now = 'a'
puts a.map_with_index { |x, i|
  if x == 0
    now.tap { now += 1 }
  else
    c1, c2 = now, now + 1
    now += 2
    "#{c1}#{c2}" * x + c1
  end
}.join