There are 64 students in the fifth grade of Linjiang Primary School who have subscribed to newspapers, 28 of whom subscribed to the mathematics newspaper, 41 to the Chinese newspaper, 20 to the English newspaper, and 10 to both the mathematics and Chinese newspapers. At the same time, 12 people subscribed to the mathematics newspaper and the English newspaper, and 12 people also subscribed to the Chinese newspaper and the English newspaper. How many people subscribe to all three newspapers?
临江小学五年级有64名学生订了报纸，其中订数学报的有28人，订语文报的有41人，订英语报的有20人，同时订数学报、语文报的有10人，同时订数学报、英语报的有12人，同时订语文报、英语报的也是12人．问三种报都订的有多少人？
<gadget id="calculator">10 + 12 + 12</gadget>
<output>34</output>

<gadget id="calculator">20 - 64</gadget>
<output>-44</output>

<gadget id="calculator">28 + 41 + (-44)</gadget>
<output>25</output>

<gadget id="calculator">34 - 25</gadget>
<output>9</output>

<result>9</result>