The town of Mansfield sold 10-year bonds with a redemption value of $5000 to finance the sewer system in the town. These bonds have semiannual coupons with a coupon rate of 10%. When amortizing such a bond, the amount of principal repaid in the second period (that is, at the end of the first year) is $57. Find the outstanding balance (also called the book value) of the bond after two years.