Put 10 small balls of red, white, green and blue colors in the bag, and ensure that 4 small balls of the same color are taken out, at least how many small balls should be taken out.
在袋子里放入红、白、绿、蓝四种颜色的小球各10个，要保证取出4个颜色相同的小球，至少应取出多少个小球．
<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">12 + 1</gadget>
<output>13</output>

<result>13</result>