Remove two trump cards from a deck of cards, leaving 52 cards. At least how many cards must be drawn from it to ensure that there are cards of all four suits? Try to explain why.
从一副扑克牌中去掉两张王牌，还有52张牌．至少从中摸出多少张牌，才能保证四种花色的牌都有？试着说明理由．
<gadget id="calculator">13 * 3</gadget>
<output>39</output>

<gadget id="calculator">39 + 1</gadget>
<output>40</output>

<result>40</result>