Game of fetching matches: There are 16 matches. Two people take turns to fetch matches. Each time they can only fetch 1, 2 or 3 matches. Whoever gets the last match wins. How can you be sure to win?
取火柴游戏：有16根火柴，两人轮流取火柴，每次只能取1根、2根或3根，不可以不取．谁取到最后一根火柴，谁就获胜．怎样才能确保获胜？
<gadget id="calculator">1 + 3</gadget>
<output>4</output>

<gadget id="calculator">16 / 4</gadget>
<output>4</output>

<result>4</result>