A bag is filled with 10 small balls of the same shape and color divided into three types: red, yellow, and white. At least how many small balls must be drawn to ensure that there are four small balls of the same color.
一个袋子里装有形状相同颜色分为红、黄、白三种的小球各10个，至少要摸出多少个小球才能保证有四个小球的颜色相同．
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">9 + 1</gadget>
<output>10</output>

<result>10</result>