Build number and Elastic version env variables

Hi,

I am following the instructions as per the link:
https://github.com/elastic/observability-examples/blob/main/Elastiflix/README.md

There is a step for modifying the .env file. However, it does not mention the setting of BUILD_NUMBER and ELASTIC_VERSION variables.

Without those, I am not able to run the _docker compose_ command for Elastic instrumented:
_cd Elastiflix
docker-compose -f docker-compose-elastic.yml up -d --no-build_

What values should be specified there? I have a cloud trial for Elastic with the APM (plus Search and other components) running on an AWS deployment.

How do I find valid values for these two so that build process can work?