Build a CSV sorter in the sandbox called csv_sorter.py.

It reads records from standard input. Records are separated by two semicolons
(`;;`). Each record is `id,name` (an integer id, a comma, then a name).

It must print the records sorted by id ascending — one per line, in the exact
same `id,name` format. Sorting must be STABLE: when two records share the same
id, they must keep their original relative order.

Example input:
  3,bob;;1,alice;;1,zoe;;2,carol

Example output:
  1,alice
  1,zoe
  2,carol
  3,bob

Handle empty input (print nothing), duplicate ids (stable order), and ids up to
10 digits. Test it against the verification oracle before replying DONE.
When the goal is met and verified, reply exactly: DONE.
