l=1;
Point(1) = {0.0,0.0,0.0,l};
Point(2) = {1,0.0,0.0,l};
Point(3) = {1,1,0,l};
Point(4) = {0,1,0,l};
Line(1) = {1,2};
Line(2) = {2,3};
Line(3) = {3,4};
Line(4) = {4,1};
Line Loop(5) = {2,3,4,1};
Plane Surface(6) = {5};
Physical Surface(7)={6};
