Adding parentheses to the formula 5-2+1 will change the calculation result by how much
给算式5-2+1添上括号计算结果发生改变的是多少
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<result>2</result>