How create project into subgroup using API

Hi,
i need create project into subgroup using API, is possibile? For project into group i use:

curl -v -H "Content-Type:application/json" https://gitlab.example.com/api/v3/projects?private_token=12345 -d "{ \"name\": \"project_name\",\"namespace_id\": \"555\" }"

I tried to view subgroups id with

https://gitlab.example.com/api/v3/groups/{id_group}/subgroups but have an error 404

I’ve resolved, use v4 api

https://gitlab.example.comapi/v4/groups