You can validate the input before using it.

    if '_' in s: raise ValueError

or

    if not re.fullmatch('[0-9]+', s): raise ValueError

Do you want to accept "۱۲۳۴" or "       12       "? If not then validate the input before using int().

Also, do not use ast.literal_eval() with untrusted input without validation. It is not a "safe eval" and may even crash the interpreter.