Share the Ruins Preservation

Example

Input

8 -10 0 -10 5 -5 5 -5 0 10 0 10 -5 5 -5 5 0

Output

50

inputFormat

Input

8 -10 0 -10 5 -5 5 -5 0 10 0 10 -5 5 -5 5 0

outputFormat

Output

50

样例

8
-10 0
-10 5
-5 5
-5 0
10 0
10 -5
5 -5
5 0

50