The kindergarten bought 4 different toys, and each child can choose any two of them, but they cannot be the same. At least how many children have to go to get it, so as to ensure that the toys that two of them are holding are exactly the same? (Think about how many different situations there are in choosing two out of 4 different toys)
幼儿园买来4中不同的玩具，每位小朋友可以任意选择两件，但不能是一样的．至少有几位小朋友去拿，才能保证其中有两位小朋友所拿的玩具是完全相同的？(想一想，从4种不同的玩具中选两种共有几种不同的情况)
<gadget id="calculator">6 + 1</gadget>
<output>7</output>

<result>7</result>