Maximum Revenue

Chef runs a shop. He has $N$ customers who are going to visit him on a day. The $I$-th customer is willing to pay a maximum of $P_I$ for his famous ice-cream that day The price for his ice-cream on the respective day is $C$ Only those people who are willing to spend an amount $P_I \geq C$ on that day will buy his ice-cream. Chef is honest in his work ethics and will charge the same amount $C