#!/usr/local/bin/perl -w
while(<DATA>){chomp,m/^(\d+)\s+(.*)/,$p[$1]=$2}
{redo if ($p[++$pc] eq undef); if($p[$pc]=~
/^(?:\s)*FOR\s+(\w+)(?:\s)*=(?:\s)*(\d+)(?:\s)*TO(?:\s)*(\d+)/x
){$var{$1}=[$pc,$2,$3];}elsif($p[$pc]=~/^(?:\s)*PRINT\s+'(.*)'/x
){print "$1\n";}elsif($p[$pc]=~/^(?:\s)*NEXT\s+(\w+)/x){die
"variable $1 not defined!" if !$var{$1};$var{$1}->[1]++;$pc=$var
{$1}->[0] if $var{$1}->[1]<=$var{$1}->[2];}elsif($p[$pc]=~
/^(?:\s)*END/x){exit}redo}

__DATA__
10  REM ****** BASIC PROGRAM *******
20
30  FOR I = 1 TO 5
40    FOR J = 1 TO 5
50      PRINT 'I LOVE GW-BASIC!'
60    NEXT J
70  NEXT I
80
90 END