Special Missions

You are playing a game with $N$ missions to complete. The $i$-th mission pays $A_i$ coins. You can choose whether to complete each mission or not, and also the order in which you want to complete them. However, some of the missions are special ones, and to access them you need to pay a one-time fee to a wizard, of $C$ coins. (You only need to pay once, not per every special mission you wish to co