How many times did the 3 children greet each other when they met?
3个小朋友见面互相打招呼，共打了多少次次．
<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">3 * 1</gadget>
<output>3</output>

<result>3</result>