"...only report any errors if there are any"

If so, why not something simple like this:

while (<IN>) {
    print qq($1\n) if /^(E)/;
    print qq($1\n) if /^(G)/;
    die $1 if /^(h)/;
}
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Or do i still misunderstand the specs?

Best regards, Karl

use strict;
use warnings;
my $infile  = shift;
my $found_E = 0;
my $sets    = 0;
open my $ifh, '<', $infile;
while(<$ifh>) {
  if (/^E/) {
    $found_E = 1;
    next;
  }
  if ($found_E) {
    if (/^G/) {
       $sets += 1;
       $found_E = 0;
       next;
    }
    if (/^h/) {
      print "Error! Found h before G\n";
      exit;
    }
  }
}
close($ifh);
printf "Found %d sets from E to G uninterrupted by h\n",$sets;
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