Set A of 8 positive integers may have the same element and have 36. And set B of 8 positive integers must have different elements and have 36. When m and n are the greatest possible differences between 36 and other elements’ sums in set A and set B, respectively, m-n=?	Choose the correct choice from the following answers:
A) 20
B) 21
C) 23
D) 25
E) 26
This is maximum-minimum. Hence, 36-(1+1+1+1+1+1+1)=29 and   36-(1+2+3+4+5+6+7)= 
<gadget id="calculator">  36-(1+2+3+4+5+6+7)</gadget>
<output>8</output>
8. So, 29-8=21. The correct answer is 21.
<result>B</result>
Set A of 8 positive integers may have the same element and have 36. And set B of 8 positive integers must have different elements and have 36. When m and n are the greatest possible differences between 36 and other elements’ sums in set A and set B, respectively, m-n=?