A road AC turns at B. The length of AB is 630 meters, and the length of BC is 560 meters. Street lights are installed at equal distances on both sides of this road. Lights must be installed at A, B, and C. How many lights should be installed on this road at least? ．
一条路AC在B处转弯，AB长630米，BC长560米，在这条路的两侧等距离的安装路灯，A、B、C三处必须装灯，这条路最少安多少盏灯．
<gadget id="calculator">2 * 5 * 7</gadget>
<output>70</output>

<gadget id="calculator">630 / 70</gadget>
<output>9</output>

<gadget id="calculator">9 + 1</gadget>
<output>10</output>

<gadget id="calculator">560 / 70</gadget>
<output>8</output>

<gadget id="calculator">8 + 1</gadget>
<output>9</output>

<gadget id="calculator">9 - 1</gadget>
<output>8</output>

<gadget id="calculator">10 + 8</gadget>
<output>18</output>

<gadget id="calculator">18 * 2</gadget>
<output>36</output>

<result>36</result>