Kupno u NPC

on leftclick on entity:
	if clicked entity's name is "&cXD":
		open chest with 1 row named "&cXD" to player
		set player's current inventory's slot 0 to diamnd named "Diax"
on inventory click:
	if inventory name of player's current inventory is "&cXD":
		cancel event
		wait 1 tick
		close player's inventory
		if clicked slot is 0:
			add 1 diamond to player
			remove 20 from player's balance

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