It is known that a*b+3=x, where a and b are prime numbers less than 1000, and x is an odd number, then what is the maximum value of x.
已知a*b+3=x，其中a、b均为小于1000的质数，x是奇数，那么x的最大值是多少．
<gadget id="calculator">2 * 997</gadget>
<output>1_994</output>

<gadget id="calculator">1_994 + 3</gadget>
<output>1_997</output>

<result>1_997</result>