@Override
	public void setStackInSlot(int slot, ItemStack stack) {
		if(stack != null)
			if(!stack.getItem().equals(Items.grease))
				return;

		if(inventory[0] == null)
			inventory[0] = stack;

		else if (stack == null && inventory[0] != null)
			inventory[0] = null;

		else if(inventory[0].getItem().equals(stack.getItem()))
			inventory[slot].stackSize += stack.stackSize;
		else
			System.out.println("something tried to replace the existing item" + inventory[slot].getItem().getUIN() +
					" by "+ stack.getItem().getUIN() );

	}