Arbitrarily add parentheses in the formula 9+8-7*6/5+4-3*2/1, so that the calculation result N is a natural number, what is the minimum value of N?
在算式9+8-7*6/5+4-3*2/1中任意加括号，使得计算结果N是自然数，N的最小值是多少．
<gadget id="calculator">8 - 7</gadget>
<output>1</output>

<gadget id="calculator">1 * 6</gadget>
<output>6</output>

<gadget id="calculator">9 + 6</gadget>
<output>15</output>

<gadget id="calculator">15 / 5</gadget>
<output>3</output>

<gadget id="calculator">2 / 1</gadget>
<output>2</output>

<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">4 - 6</gadget>
<output>-2</output>

<gadget id="calculator">3 + (-2)</gadget>
<output>1</output>

<result>1</result>