\overline{ABCD} represents a four-digit number, \overline{EFG} represents a three-digit number, A, B, C, D, E, F, G represent different numbers from 1 to 9, known \overline{ABCD }+\overline{EFG}=1997, what is the difference between the maximum value and the minimum value of the product \overline{ABCD}*\overline{EFG}.
\overline{ABCD}表示一个四位数，\overline{EFG}表示一个三位数，A、B、C、D、E、F、G代表1至9中不同的数字，已知\overline{ABCD}+\overline{EFG}=1997，问乘积\overline{ABCD}*\overline{EFG}的最大值与最小值差是多少．
<gadget id="calculator">1_238 * 759</gadget>
<output>939_642</output>

<gadget id="calculator">1_759 * 238</gadget>
<output>418_642</output>

<gadget id="calculator">939_642 - 418_642</gadget>
<output>521_000</output>

<result>521_000</result>