Fifty willow trees were planted on the embankment of the Qinhuai River, and a leisure bench was placed between every two willow trees, how many benches were placed.
秦淮河一侧的河堤上栽了50棵柳树，每两棵柳树中间放一张休闲长椅，放了多少张长椅．
<gadget id="calculator">50 - 1</gadget>
<output>49</output>

<result>49</result>