20 children stand in a row. Counting from left to right, Yang Tao ranks third, and counting from right to left, Qian Hui ranks fourth. How many people are there between Yang Tao and Qian Hui?
20个小朋友站成一排．从左往右数，杨涛排第3，从右往左数，钱辉排第4，杨涛和钱辉之间一共有多少人．
<gadget id="calculator">20 - 3 - 4</gadget>
<output>13</output>

<result>13</result>