Source google image: http://4.bp.blogspot.com/-VwLioSBOyXo/U6XCl6YGudI/AAAAAAAABLY/WYCpBTStSDQ/s1600/100-doors-3-level-57.jpg
100 doors puzzle level 3
Source google image: http://4.bp.blogspot.com/-VwLioSBOyXo/U6XCl6YGudI/AAAAAAAABLY/WYCpBTStSDQ/s1600/100-doors-3-level-57.jpg