10 DIM A$(20,20)
 20 FOR I=1 TO 20
 30 FOR J=1 TO 20
 40 LET A$(I,J)=CHR$ (1+INT (RND*20))
 50 NEXT J
 60 NEXT I
 70 FOR I=1 TO 20
 80 FOR J=1 TO 20
 90 PRINT CODE A$(I,J);" ";
100 IF CODE A$(I,J)=20 THEN GOTO 130
110 NEXT J
120 NEXT I