paypal - Rest C# capture error response in Payment.Create() -

i'm following rest sample (paymentwithcreditcard) , can't figure out how actual error code.

payment pymnt = new payment(); pymnt.intent = "sale"; pymnt.payer = payr; pymnt.transactions = transactions;  try {     apicontext apicontext = configuration.getapicontext();     payment createdpayment = pymnt.create(apicontext); catch (exception ex) {     // how can error code?? }            

how can tie general exception list of error codes (https://developer.paypal.com/docs/classic/api/errorcodes/)?

thanks.