403850: GYM101341 E Bonuses and Teleports

On a number axis n teleports are located in the points t_i and m bonuses are located in the points b_j. Being in the same point with a teleport, one can instantly relocate to another point with the teleport. Being in the same point with a bonus, one can instantly get this bonus.

You are in the point t₁ and must collect all the bonuses, and then return back to the point t₁. You can move along the number axis in any direction at the speed 1. How much time will it take to collect all the bonuses?

The first line contans two integers n and m separated by a space (1 ≤ n, m ≤ 200000) — the number of teleports and the number of bonuses, correspondingly.

The second line contains n integers t_i separated by a space ( - 10⁹ ≤ t_i ≤ 10⁹, t_i ≤ t_i + 1) — coordinates of the teleports in non-decreasing order.

The third line contains m integers b_j separated by a space ( - 10⁹ ≤ b_j ≤ 10⁹, b_j ≤ b_j + 1) — coordinates of the bonuses in non-decreasing order.

Output a single integer — the minimal time required to collect all the bonuses.

2 4
0 10
-1 1 9 11

8

2 2
0 10
4 6

10

1 1
1000000000
-1000000000

4000000000