Delete the closing brace } after return 0; and click run. The compiler says expected '}' at end of input. It read the entire file looking for the closing brace but never found it.
Every opening brace needs a closing brace. The main function starts with { so it must end with }. If you have nested blocks later, you will need multiple closing braces. Count carefully.
Many editors highlight matching braces when you click one. Use this feature to check your braces match. If you click { and the editor does not highlight a }, you forgot to close the block.