a, b, and c are all natural numbers, a*b=221, b*c=187, c*a=143, so how much is a+b+c=.
a、b、c都是自然数，a*b=221，b*c=187，c*a=143，那么a+b+c=多少．
<gadget id="calculator">13 + 17 + 11</gadget>
<output>41</output>

<result>41</result>