A pile of coal, 345kg was used for the first time, and 422kg was transported in, and 559kg was used for the second time, leaving 253kg. How many kilograms did this pile of coal originally have?
一堆煤，第一次用345千克，又运进422千克，第二次用去559千克，还剩253千克，这堆煤原来有多少千克？
<gadget id="calculator">559 - 422</gadget>
<output>137</output>

<gadget id="calculator">253 + 137 + 345</gadget>
<output>735</output>

<result>735</result>