10 DIM s(2000,3) 20 LET s(1,1)=3: REM M 30 LET s(1,2)=7: REM N 40 LET lev=1 50 GO SUB 100 60 PRINT "A(";s(1,1);",";s(1,2);") = ";s(1,3) 70 STOP 100 IF s(lev,1)=0 THEN LET s(lev,3)=s(lev,2)+1: RETURN 110 IF s(lev,2)=0 THEN LET lev=lev+1: LET s(lev,1)=s(lev-1,1)-1: LET s(lev,2)=1: GO SUB 100: LET s(lev-1,3)=s(lev,3): LET lev=lev-1: RETURN 120 LET lev=lev+1 130 LET s(lev,1)=s(lev-1,1) 140 LET s(lev,2)=s(lev-1,2)-1 150 GO SUB 100 160 LET s(lev,1)=s(lev-1,1)-1 170 LET s(lev,2)=s(lev,3) 180 GO SUB 100 190 LET s(lev-1,3)=s(lev,3) 200 LET lev=lev-1 210 RETURN