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(0);
  }
  redo;
}

__DATA__
1   REM ****** BASIC PROGRAM *******
2   REM *** Print Text 500 times ***
3
10  FOR I = 1 TO 500
20  PRINT 'I will not throw paper airplanes in class.'
30  NEXT I
31
32  REM ****** I CAN DO NESTED LOOP TOO ******
33
40  FOR I = 1 TO 2
50    FOR J = 1 TO 5
60      FOR K = 1 TO 5
70        FOR L = 1 TO 10
80          PRINT 'I will not throw paper airplanes in class.'
90        NEXT L
100     NEXT K
110   NEXT J
120 NEXT I
130 END