The school organizes all teachers and students to go to the cinema to watch movies. The seats in the cinema are stepped, and each row has two more seats than the front row. After arriving at a cinema, everyone sits in their own seats, and Xiaoying happens to sit in the last row. There are no empty seats at the corner of the row, how many people will there be? Xiaoying took out her movie ticket and looked at it, it was No. 58 in the 20th row. Kids, help Xiaoying do the math!
学校组织全校师生去电影院看电影，电影院的座位是阶梯式的，每排都比前排多两个座位，到了一电影院后，大家各自坐在自己的位置上，小颖恰好坐在最后一排的角落处，座无虚席，到底会有多少人呢？小颖拿出自己的电影票看了一下是第20排58号．小朋友们快帮小颖算一算吧!
<gadget id="calculator">20 - 1</gadget>
<output>19</output>

<gadget id="calculator">2 * 19</gadget>
<output>38</output>

<gadget id="calculator">58 - 38</gadget>
<output>20</output>

<gadget id="calculator">58 + 20</gadget>
<output>78</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">78 * 10</gadget>
<output>780</output>

<result>780</result>