Mark src as Sources Root: Right-click on the src folder, select Mark Directory as → Sources Root.

Check Run Configuration: Go to the run configuration dropdown, select Edit Configurations, and ensure Main class is set to CWA_01_INTRO.

Rebuild the Project: Go to Build → Rebuild Project.

Check Output Path: In File → Project Structure, verify the output path is correct.

Invalidate Caches: Go to File → Invalidate Caches / Restart, and choose Invalidate and Restart.