There are 10 red wooden blocks, 10 yellow wooden blocks, and 10 white wooden blocks in a square box. They are all the same shape and size. I was blindfolded to take the wooden blocks from the box, in order to ensure that there are 3 pieces of the same color , then how many pieces of wood should I take out from the box at least.
一个方盒子中放着10块红色木块，10块黄色木块，10块白色木块，它们的形状大小都一样，我被蒙住眼睛去方盒中取木块，为了确保有3块同色，那么我应从方盒中至少取出多少块木块．
<gadget id="calculator">2 * 3</gadget>
<output>6</output>

<gadget id="calculator">6 + 1</gadget>
<output>7</output>

<result>7</result>