Draw 212 straight lines on the plane, how many points of intersection can these lines form at most?
在平面上画212条直线，这些直线最多能形成多少个交点．
<gadget id="calculator">212 - 1</gadget>
<output>211</output>

<gadget id="calculator">212 / 2</gadget>
<output>106</output>

<gadget id="calculator">211 * 106</gadget>
<output>22_366</output>

<result>22_366</result>