In a Go match, a total of 5 students participate in the game, if every two players have to play one game, how many games will be played in total.
在一次围棋比赛中，共有5名同学参加比赛，如果每两个选手都要比赛一场，一共要比赛多少场．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

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

<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<result>10</result>