Cover the Polygon with Your Disk

Example

Input

4 4 0 0 6 0 6 6 0 6

Output

35.759506

inputFormat

Input

4 4 0 0 6 0 6 6 0 6

outputFormat

Output

35.759506

样例

4 4
0 0
6 0
6 6
0 6

35.759506