I have created a Cross object Custom formula field that displays the Address .Here is the format to display the address field.

Account.BillingStreet  & BR() &
Account.BillingCity & ", "
 & Account.BillingState  & " " &
Account.BillingPostalCode  & BR()
& Account.BillingCountry

Now my question is there is a Comma in the formula and it displays, when the BillingStreet,BillingCity,etc., fields are empty.

How to resolve this?