A building has 18 floors on the ground and 2 floors underground. Someone takes the elevator from the -2 floor to the 17th floor. How many floors does the elevator go up in total?
某大楼地上共有18层，地下共有2层，某人乘电梯从-2层升至17层，电梯一共升了多少层．
<gadget id="calculator">17 - (-2) - 1</gadget>
<output>18</output>

<result>18</result>