Look at type

catch (System.OverflowException e)
{ ...

e is my variable name it is short for exception. It is not obligatory to use any name if you wanna catch OverflowException without more information.

Use

checked

Like in example bellow:

    try
    {
        // The following line raises an exception because it is checked.
        z = checked(maxIntValue + 10);
    }
    catch (System.OverflowException e)
    {
        // The following line displays information about the error.
        Console.WriteLine("CHECKED and CAUGHT:  " + e.ToString());
    }

checked on msdn