10 GOTO 200 20 FOR I=CB TO CE 21 Y=C39-I 22 COLOR=I 30 FOR J=CB TO CE 50 X=C39-J 80 PLOT J,I 82 PLOT I,J 84 PLOT X,Y 86 PLOT Y,X 90 NEXT J 100 NEXT I 102 CE=CE-1 103 CB=CB+1 104 IF CB>CE THEN GOTO 201 110 GOTO 20 200 GR 201 C0=0 202 CB=C0 210 C39=39 211 CE=C39 230 GOTO 20