In the 2010 FIFA World Cup in South Africa, Spain, Chile, Honduras, and Switzerland were in Group H. The round-robin system was adopted in the group (every two teams competed one game). How many games will there be in Group H in the group stage?
2010年南非世界杯足球赛中，西班牙、智利、洪都拉斯、瑞士同在H组，小组中采用循环赛制(每两队间比一场)，小组赛中H组共要进行几场比赛？
<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>