There are four teams in Group C of the 2002 World Cup: Brazil, Turkey, China, and Costa Rica. Every two teams will play one game. How many games will they play in total?
2002年世界杯足球赛C组球队有巴西、士耳其、中国、哥斯达黎加四支球队，每两个球队踢一场，一共要踢多少场．
<gadget id="calculator">4 - 1</gadget>
<output>3</output>

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

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

<result>6</result>