World of Darkraft: Battle for Azathoth

Roma is playing a new expansion for his favorite game World of Darkraft. He made a new character and is going for his first grind.

Roma has a choice to buy exactly one of $$$n$$$ different weapons and exactly one of $$$m$$$ different armor sets. Weapon $$$i$$$ has attack modifier $$$a_i$$$ and is worth $$$ca_i$$$ coins, and armor set $$$j$$$ has defense modifier $$$b_j$$$ and is worth $$$cb_j$$$ coins.

After choosing his equipment Roma can proceed to defeat some monsters. There are $$$p$$$ monsters he can try to defeat. Monster $$$k$$$ has defense $$$x_k$$$, attack $$$y_k$$$ and possesses $$$z_k$$$ coins. Roma can defeat a monster if his weapon's attack modifier is larger than the monster's defense, and his armor set's defense modifier is larger than the monster's attack. That is, a monster $$$k$$$ can be defeated with a weapon $$$i$$$ and an armor set $$$j$$$ if $$$a_i > x_k$$$ and $$$b_j > y_k$$$. After defeating the monster, Roma takes all the coins from them. During the grind, Roma can defeat as many monsters as he likes. Monsters do not respawn, thus each monster can be defeated at most one.

Thanks to Roma's excessive donations, we can assume that he has an infinite amount of in-game currency and can afford any of the weapons and armor sets. Still, he wants to maximize the profit of the grind. The profit is defined as the total coins obtained from all defeated monsters minus the cost of his equipment. Note that Roma must purchase a weapon and an armor set even if he can not cover their cost with obtained coins.

Help Roma find the maximum profit of the grind.