Add a number to the numerator and denominator of the fraction (2011/2013) at the same time, so that the new fraction is reduced to (2013/2014), then what should be the added number.
分数(2011/2013)的分子和分母同时加上一个数，使新分数约分后为(2013/2014)，那么加上的数应是多少．
<gadget id="calculator">4_026 - 2_011</gadget>
<output>2_015</output>

<result>2_015</result>