15 cards, each with 3 different Chinese characters written on them, the Chinese characters on any 2 cards are not exactly the same; out of any 6 cards, there must be 2 cards with the same Chinese characters on them. Q: How many different Chinese characters are there at most on these 15 cards?
15张卡片，每张卡片上写有3个不同的汉字，任意2张上的汉字不完全相同；任意6张中，一定有2张，它们上面有共同的汉字．问：这15张卡片上最多有多少个不同的汉字？
<gadget id="calculator">45 - 10</gadget>
<output>35</output>

<result>35</result>