A wide river has pillars of possibly different heights standing out of the water. They
are arranged in a straight line from one bank to the other. We would like to build a
bridge that uses the pillars as support. To achieve this we will select a subset of pillars
and connect their tops into sections of a bridge. The subset has to include the first and
the last pillar.
The cost of building a bridge section between pillars and
is
as we want
to avoid uneven sections, where
is the height of the pillar
. Additionally, we will also
have to remove all the pillars that are not part of the bridge, because they obstruct the
river traffic. The cost of removing the
pillar is equal to
. This cost can even be
negative—some interested parties are willing to pay you to get rid of certain pillars. All
the heights
and costs
are integers.
What is the minimum possible cost of building the bridge that connects the first and last pillar?
Input
The first line contains the number of pillars, . The second line contains pillar heights
in the order, separated by a space. The third line contains
in the same order, the
costs of removing pillars.
Output
Output the minimum cost for building the bridge. Note that it can be negative.
Constraints
Subtask 1 (30 points)
Subtask 2 (30 points)
- optimal solution includes at most 2 additional pillars (besides the first and last)
Subtask 3 (40 points)
- no additional constraints
Sample Input 1
6
3 8 7 1 6 6
0 -1 9 1 2 0
Sample Output 1
17
Comments
Since the original data were weak, an additional test case was added to subtask
.