defmodule Main do
    def solve("", acc), do: acc

    def solve(s, acc) do
        l = String.at(s, -1)
        ss = String.slice(s, 0..-2)
        ac = append(l, acc, String.length(acc))
        solve(ss, ac)
    end

    def append(l, acc, len) when rem(len, 4) == 3 do
        l <> "," <> acc
    end
    def append(l, acc, _) do
        l <> acc
    end

    def main do
        s = IO.gets("") |> String.trim
        IO.puts solve(s, "")
    end
end