There are 1, 3, 5, and 7 black, white, yellow, and red balls respectively, and they are mixed together. If you want to take two pairs of balls with different colors from these balls in the dark, how many balls must be taken at least to ensure that Require?
黑色、白色、黄色、红色的球分别有1个、3个、5个和7个，混杂在一起，黑暗中想从这些球中取出颜色不同的两对球，至少要取多少个才能保证达到要求？
<gadget id="calculator">7 + 3 + 1</gadget>
<output>11</output>

<result>11</result>