Add error handling for invalid user input in main.py

[maks-ivanov]

Currently, main.py asks the user to input data via input() calls. If the user writes something unexpected, the whole script will fail.
Add exception handling blocks around input so when user input is bad, it prompts to try again.

[maks-ivanov]

Planner Agent Output: 1. Use the 'git-new-branch' tool with the input 'error-handling' to create a new branch called 'error-handling'.
2. In main.py, identify all input() calls.
3. For each input() call, wrap it in a while loop and a try-except block.
4. In the try block, read the user input and validate it. If it's valid, break the loop.
5. In the except block, print an error message and continue the loop.
6. Commit the changes to main.py using the 'git-commit' tool with the input 'main.py'.
7. Create a pull request for the 'error-handling' branch using the 'git-create-pull-request' tool.