Uncle Liu took the elevator from the 1st floor to the 7th floor to get materials from the general manager's office, then took the elevator down 3 floors to the finance department to receive wages, then took the elevator up 2 floors to pay employees, and then took the elevator down 4 floors Back to his office. What floor is Uncle Liu's office on?
刘叔叔乘电梯从1层上到7层去总经理办公室取材料，然后坐电梯下降了3层去财务部领工资，接着又坐电梯上升了2层给员工发工资，之后坐电梯下降了4层回到自己的办公室．刘叔叔的办公室在几层？
<gadget id="calculator">7 - 3</gadget>
<output>4</output>

<gadget id="calculator">2 - 4</gadget>
<output>-2</output>

<gadget id="calculator">4 + (-2)</gadget>
<output>2</output>

<result>2</result>