Someone tore off the calendars of the previous five days, and the sum of the numbers of the five days is 45, so what is this day?
某人撕下前五天的日历，这五天的日历的号数的和是45，那么这一天是多少．
<gadget id="calculator">45 - 1 - 2</gadget>
<output>42</output>

<gadget id="calculator">2 + 1 + 42</gadget>
<output>45</output>

<gadget id="calculator">1 + 1 + 1 + 1 + 1</gadget>
<output>5</output>

<gadget id="calculator">45 / 5</gadget>
<output>9</output>

<gadget id="calculator">9 + 3</gadget>
<output>12</output>

<result>12</result>