lc = 1;
Point(1) = {0,0,0,lc};
Point(2) = {1,0,0,lc};
Point(3) = {1,1,0,lc};
Point(4) = {0,1,0,lc};
Point(5) = {0,0,1,lc};
Point(6) = {1,0,1,lc};
Point(7) = {1,1,1,lc};
Point(8) = {0,1,1,lc};

Line(1) = {1,2};
Line(2) = {2,3};
Line(3) = {3,4};
Line(4) = {4,1};
Line(5) = {5,6};
Line(6) = {6,7};
Line(7) = {7,8};
Line(8) = {8,5};
Line(9) = {1,5};
Line(10) = {2,6};
Line(11) = {3,7};
Line(12) = {4,8};

Line Loop(20) = {-1,-2,-3,-4};
Plane Surface(30) = {20};
Line Loop(21) = {-8,-7,-6,-5};
Plane Surface(31) = {21};
Line Loop(22) = {1,10,-5,-9};
Plane Surface(32) = {22};
Line Loop(23) = {10,6,-11,-2};
Plane Surface(33) = {23};
Line Loop(24) = {11,7,-12,-3};
Plane Surface(34) = {24};
Line Loop(25) = {4,9,-8,-12};
Plane Surface(35) = {25};

Physical Surface(40) = {30,31,32,33,34,35};