1 in addition , holders of our $ 400.0 4.50% ( 4.50 % ) notes may require us to repurchase their 4.50% ( 4.50 % ) notes for cash at par in march 2008 . these notes will mature in 2023 if not converted or repurchased . redemption of long-term debt in august 2005 , we redeemed the remainder of our 7.875% ( 7.875 % ) senior unsecured notes with an aggregate principal amount of $ 250.0 at maturity for a total cost of $ 258