a, b, c, d are four different natural numbers, and a*b*c*d=2790, what is the minimum of a+b+c+d.
a、b、c、d是四个不同的自然数，且a*b*c*d=2790，a+b+c+d最小是多少．
<gadget id="calculator">2 * 3</gadget>
<output>6</output>

<gadget id="calculator">3 + 5 + 6 + 31</gadget>
<output>45</output>

<result>45</result>