Laser Cutter

Example

Input

3 0 1 0 0 0 1 0 1 0 2 0 2 0 3

Output

6.0000000000000000

inputFormat

Input

3 0 1 0 0 0 1 0 1 0 2 0 2 0 3

outputFormat

Output

6.0000000000000000

样例

3
0 1
0 0 0 1
0 1 0 2
0 2 0 3

6.0000000000000000