sub
example {
  $foo = "[&#\$]";
  $regex = "a\\d+[ars]{2,4}(aa|ab|ac)";
  $string="wle;fnaekf;fla;lkcnovnifa  ";
  $min = $regex."\$"."foo";
  if ($min !~ /\$$/) {
    $min .= '$';
  }
  $match = 0;
  $tot = length($string);
  $index = $tot;
  print "index is $index\n";
  while (1) {
    print "min is $min\n";
    eval {
      if ($string =~ m/$min/g) {
        $index = pos $string;
        $match = 1;
      }
    };
#   print "err is $@\n";
    last if $match;
    $min =~ s/..$//;
    last if $min eq "";
    if ($min !~ /\$$/) {
      $min .= '$';
    }
  }
  return $index;
}

$ind = example();