There are 3 balls whose masses are 13 grams, 16 grams, and 19 grams respectively; if the mass of the second ball is recorded as 0 grams, then the mass of the lightest ball should be recorded as - how many grams.
有3个球的质量分别为13克、16克、19克；如果第二个球的质量记作0克，那么最轻的球质量应记作-多少克．
<gadget id="calculator">16 - 13</gadget>
<output>3</output>

<result>3</result>