Grandpa Wang wants to fence a rectangular vegetable field (one side against the wall). The vegetable field is 68 meters long and 39 meters wide. How many meters does Grandpa Wang need to fence at least?
王爷爷想给长方形菜地围上篱笆(一面靠墙)，菜地长68米，宽39米，王爷爷至少需要围多少米？
<gadget id="calculator">39 * 2</gadget>
<output>78</output>

<gadget id="calculator">68 + 78</gadget>
<output>146</output>

<result>146</result>