The school held a sports meeting, and 10 red flags were arranged on the side of the playground. If one blue flag, one yellow flag and one colored flag are to be arranged between every two red flags, how many flags are needed in total.
学校开运动会，在操场边布置了10面红色的旗帜．如果现在要在每两面红旗之间再布置上1面蓝旗、1面黄旗和1面彩旗，共需要再准备多少面旗帜．
<gadget id="calculator">1 + 1 + 1</gadget>
<output>3</output>

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

<gadget id="calculator">3 * 9</gadget>
<output>27</output>

<result>27</result>