#!/usr/bin/perl
use strict; use warnings;
my @fh;
for my $file (@ARGV) {
	open my $fh, "<", $file or die "can't open $file\n";
	push @fh, $fh;
}
my $block_size = 4096;
while (1) {
	my $done = 1;
	my $block;
	for my $fh (@fh) {
		read $fh, my $this_block, $block_size or next;
		$done = 0;
		$block |= $this_block;
	}
	last if $done;
	print $block;
}