There was a group of pigeons, and the one on the tree said to the ones on the ground: "If one of you flies up, the pigeons on the ground will be 1/3 of the whole flock. If one of you flies down from the tree, all the pigeons on and under the tree will There are as many pigeons. How many pigeons were there in the tree?
有一群鸽子，树上的对地上的说："你们中的一只飞上来，则地上的鸽子就是整个鸽群的1/3，若从树上飞下去一只，则树上、树下的鸽子就一样多了．树上原来有多少只鸽子．
<gadget id="calculator">1 + 1</gadget>
<output>2</output>

<gadget id="calculator">2 + 2</gadget>
<output>4</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3) - (1/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">4 / (1/3) / 2</gadget>
<output>6</output>

<gadget id="calculator">6 + 1</gadget>
<output>7</output>

<result>7</result>