Four packets P, Q, R and S, three wallets A, B and C are kept on a table one after the other in a row from left to right. Wallet C has as many items to its left as to its right. No packet is at any extreme end of the row.Packet P is kept to the immediate left of packet R. Packet P is to the immediate right of wallet A. What is kept third from left end of the row on the table?