pog loves szh II

Pog and Szh are playing games.There is a sequence with $n$ numbers, Pog will choose a number A from the sequence. Szh will choose an another number named B from the rest in the sequence. Then the score will be $(A+B)$ mod $p$.They hope to get the largest score.And what is the largest score?

Several groups of data (no more than $5$ groups,$n \geq 1000$).

For each case:

The following line contains two integers,$n(2 \leq n \leq 100000)$，$p(1 \leq p \leq 2^{31}-1)$。

The following line contains $n$ integers $a_i(0 \leq a_i \leq 2^{31}-1)$。

For each case,output an integer means the largest score.

4 4
1 2 3 0
4 4
0 0 2 2

3
2

BestCoder Round #43