Finding a Hidden Benchmark Value

You are given array A with N number A= [a0, a1 .. aN-1] and array B with M numbers, B= [b0, b1 … bM-1]. (1≤ N, M≤ 10 ^5,1 ≤ ai≤ 10^8, 1≤ bj ≤ 10^8)
SA and SB represent the respective scores of A and B, and each score is defined as the total score of the elements in each array.

When calculating SA and SB this way, calculate D which makes the biggest difference between the two. (Caution: It is Not the absolute value)
If there is more than one D that maximizes the difference between SA and SB, Calculate the smallest one.
Case 1:
A = (6,10,9,7,8)
B = (4,1,5,3,2)

Expected Answer :5
Answer Explanation: When D is 5, the score of A and B are 10 and 5, respectively. Then , the value of SA-SB is 5 which is also maximum.

Case 2:
A= (3,2,1)
B = (5,6)
Expected Answer: 0
Answer Explanation: When D is 0, the scores of A and B are 6 and 4 respectively. Then , the value of SA-SB is 2 which is also maximum.

Case 3:
A= (10,6,3)
B = (3,3,10,3,2,11)
Expected Answer: 3
Answer Explanation: When D is 3, the scores of A and B are 5 and 8 respectively. Then, the value of SA-SB is -3 which is also maximum. Although the maximum value of SA-SB is -3 when D is 11 or 12 as the score of A and B are 3 and 6, respectively, the answer is 3 because 3 is smaller than 11.

Case 4:
A= (1,2)
B = (5,6,7,8)
Expected Answer: 8
Answer Explanation: When D is 8, the scores of A and B are 2 and 4 respectively. Then , the value of SA-SB is -2 which is also maximum. Remember that the difference between SA and SB is not an absolute value.