use File::Temp;
my $file = shift @ARGV;

my $low=1;
chomp(my $high = `wc -l $file`);
print "File is $high lines\n";

my %tried;
while (my $next=int(($high-$low)/2)+$low) {
  last if $tried{$next}++;
  print "low: $low high: $high next: $next\n";
  my $tmp = File::Temp->new(TEMPLATE => "tmp_XXXXXX", DIR=>".");
  open(my $fh, $file) or die "Can't open $file: $!";
  while (<$fh>) {
    print $tmp "__END__\n" if $. == $next;
    print $tmp $_;
  }
  close $fh;
  $tmp->close();
  my $out = `perl -c $tmp 2>&1`;
  ( $out =~ /syntax OK/ ? $low : $high ) = $next;
}