When SuSu and his friends visited GanQuan village , something dangerous happened on them . They were trapped in a mysterious cave , what was worse ,there was a terrible monster lived in the cave , so they had to escape from the cave as quickly as possible .
But little monsters were also in the cave, as a result ,when SuSu was seen by the little monsters ,they would notice their boss to catch SuSu back.
Little monsters' visual field is showed in figure A. The grid colored red represents where the monster stands, the arrow represents which direction the monster walk to ,and the grids colored blue and red represents where the very monster can see at this moment. The monsters often walks in a straight line, and when they faces a wall or the boundary of the maze in front of him, they will cost 1 seconds to turn back, and then walk back along the straight line, until reach a wall again.
If SuSu was seen by the monsters ,it's impossible for them to escape from the cave . SuSu needs your help , please tell him the minimum time he needs to walk from the start point to the exit of the cave , be careful not to be seen by the monsters. Every seconds SuSu can move upward downward leftward and rightward , and can also make no movement.
Figure A