Four players A, B, C, and D are playing table tennis (no draw). Every two people have to play a game. After the game, the results are counted. A has won 2 games, B has won 1 game, and how many games can C win at most.
甲、乙、丙、丁四人进行乒乓球比赛(没有平局)．每两人都要赛一场，比赛结束后统计成绩，甲胜了2场，乙胜了1场，丙最多胜多少场．
<gadget id="calculator">6 - 2 - 1</gadget>
<output>3</output>

<result>3</result>