glitch-86x/C_program ? reverse-engineered prompt

Build me a simple C program in one file that I can compile and run from the terminal.

I just want a clean, working starting point in main.c, with a sensible structure and a few comments so it’s easy to understand and extend later. If you need to make a choice about what the program does, keep it small and practical, something like a basic console app with simple input and output.

Please make sure it builds without errors, handles obvious bad input gracefully, and includes any setup notes I’d need to compile it locally. If anything is unclear, go with the simplest version and keep it easy for me to modify afterward.