There are four numbers, and the sum of each three numbers is 45, 46, 49, and 52 respectively. What is the smallest number among these four numbers?
有四个数，其中每三个数的和分别是45、46、49、52，那么这四个数中最小的一个数是多少．
<gadget id="calculator">45 + 46 + 49 + 52</gadget>
<output>192</output>

<gadget id="calculator">192 / 3</gadget>
<output>64</output>

<gadget id="calculator">64 - 52</gadget>
<output>12</output>

<result>12</result>