Please help me with this problem. It is complete question with no missing components.

Problem 3

Under our usual assumptions consider a sealed-bid all-pay auction in which every buyer submits a bid, the highest bidder receives the good, and every buyer pays the seller the amount of his big regardless of whether he wins. Compare the seller's expected revenues in such an auction with the seller's expected equilibrium revenues from the usual first price auction. Derive a symmetric equilibrium bidding function for the all pay auction. Justify your answers carefully.