There is a residential building, each of which subscribes to 2 different newspapers, and the residential building subscribes to three kinds of newspapers. Among them, there are 34 copies of "Nantong Radio and Television News", 30 copies of "Yangtze Evening News", and 22 copies of "Newspaper Digest". So, how many companies subscribe to "Yangtze Evening News" and "Newspaper Digest".
有一栋居民楼，每家都订2份不同的报纸，该居民楼共订了三种报纸．其中《南通广播电视报》34份，《扬子晚报》30份，《报刊文摘》22份．那么，订《扬子晚报》和《报刊文摘》的共有多少家．
<gadget id="calculator">34 + 30 + 30</gadget>
<output>94</output>

<gadget id="calculator">94 / 2</gadget>
<output>47</output>

<gadget id="calculator">47 - 34</gadget>
<output>13</output>

<result>13</result>