Help Maya
Maya the Bee pollinates flowers in a magical meadow. The meadow can be represented as a matrix
of rows and
columns. In
row and
column there are
unpollinated flowers.
Maya will start her journey from her hive, which is located in the field in the
row and
column. In
several steps, she will visit some fields of the meadow and then return back to her hive. From each
field, Maya can move to one of its adjacent cells in one of the following directions: left, right, up or
down. Also, Maya will never leave the meadow. Each time Maya flies over some field, she pollinates
all unpollinated flowers growing on the field. But the meadow is magical! As soon as Maya leaves the
field
, all the pollinated flowers will disappear and
new unpollinated flowers will grow on that
field.
Since Maya can't fly forever, she will get tired after steps and gladly tell her adventurous story to her
bee friends. What is the maximal number of flowers Maya can pollinate if she makes exactly
steps
and ends her journey back at her hive?
Input
The first line contains positive integers ,
,
and
.
will always be even.
lines follows, each containing
integers describing amount of flowers
located in
row and
column.
The field containing the hive won’t have any flowers on it.
Output
Print the number from the task statement.
Samples
Input 1
2 2 1 1 2
0 1
2 10
Output 1
2
Input 2
2 2 1 1 4
0 5
5 10
Output 2
20
Input 3
3 3 2 2 6
5 1 0
1 0 3
1 3 3
Output 3
15
Clarification of sample tests
In the first sample Maya starts from the field , flyes to the field below, pollinates 2 flowers there, and returns
back to the hive.
In the second sample Maya start from the field and can pollinate flowers moving as follows: she moves
right, then down, then up and then left. Notice that Maya visited the field
twice, each time pollinating 5
flowers on that field.
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