local n = io.read("*n")
local p = 1
while 0 < n do
  local a = 1
  for i = 1, n do
    local v = i * (i + 1) / 2
    if n < v then break end
    a = i
  end
  io.write(string.rep(string.char(96 + p), a))
  n = n - a * (a + 1) / 2
  p = p + 1
  if p == 4 then p = 1 end
end
io.write("\n")