For a pile of goods, on average, 1 ton is left in a 6-ton cart or a 5-ton cart. What is the minimum ton of this pile of goods?
一堆货物，平均让6吨大车或5吨小车装都剩下1吨，这堆货物至少多少吨．
<gadget id="calculator">5 * 6</gadget>
<output>30</output>

<gadget id="calculator">30 + 1</gadget>
<output>31</output>

<result>31</result>