my @pre = map "../../pics/$_/", '00' .. '16';

my $offs = 0;

while ( <> ) {
	chomp;
	for my $i ( 0 .. $#pre ) {
		local $_ = $pre[ ( $i + $offs ) % @pre ] . $_;
		next if not -e;
		print;
		$offs = $i;
		last;
	}
}